Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-10-19
2004-06-29
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S087000, C345S089000
Reexamination Certificate
active
06756959
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to display driving apparatus and display apparatus module that are capable of suppressing the circuit scale and reducing the power consumption of the circuit.
BACKGROUND OF THE INVENTION
FIG. 9
is a block diagram showing a liquid crystal display apparatus of a TFT (Thin-Film Transistor) type that is a typical one of active matrix types.
The liquid crystal display apparatus is provided with a liquid crystal display section and a liquid crystal display apparatus (liquid crystal driving circuit) that drives the liquid crystal display section. The liquid crystal display section is provided with a liquid crystal panel
901
of TFT-type. The liquid crystal panel
901
is provided with a plurality of display unit elements (pixels) that are disposed in a matrix manner and an opposite electrode (common electrode)
906
.
In the mean time, the liquid crystal driving apparatus is provided with source driver
902
and gate driver
903
each of the drivers including an IC (Integrated Circuit) chip, a controller
904
, and a liquid crystal driving power source
905
.
The source driver
902
and the gate driver
903
are provided as follows, in general. More specifically, by providing, on ITO (Indium Tin Oxide) terminals that are provided so as to extend from the inside of the liquid crystal panel
901
toward its peripheral part, such as a TCP (Tape Carrier Package) that is realized by mounting the IC chip on a film which has been subjected to a predetermined wiring, and combining, or providing the IC chip directly to the ITO terminals of the liquid crystal panel
901
via an ACF (Anisotropic Conductive Film) by means of thermal bonding, and combining, the drivers are provided.
In order to further miniaturize the liquid crystal display apparatus, the controller
904
, the liquid driving power source
905
, the source driver
902
, and the gate driver
903
are combined so as to have 1-chip structure, or 2-chip structure, or 3-chip structure.
FIG. 9
shows these structures separately for respective functions.
The controller
904
outputs to the source driver
902
(a) the digitized display data (for example, RGB image signals corresponding to red, green, and blue, respectively) indicated as D in FIG.
9
and (b) respective control signals indicated as S
1
in FIG.
9
. The controller
904
also outputs respective control signals indicated as S
2
in
FIG. 9
to the gate driver
903
. The source driver
902
mainly receives the control signals such as a horizontal synchronizing signal (a latch signal Ls), a start pulse signal, and a clock signal for source driver-use. The gate driver
903
mainly receives the control signals such as a vertical synchronizing signal and a clock signal for gate driver-use. Note that a power source that drives the respective IC chips (gate driver IC and source driver IC) is omitted in FIG.
9
.
The liquid crystal driving power source
905
supplies the source driver
902
and the gate driver
903
with a voltage for liquid crystal panel display-use (a reference voltage for generating a voltage for gradation display-use).
The display data that have been externally inputted are sent to the source driver
902
via the controller
904
as the display data D that are a digital signal. The source driver
902
carries out the sampling with respect to the inputted display data D in a time—sharing manner and store the sampling result, and then carry out the D/A conversion in which the display data D is converted into the voltage for gradation display—use so as to be in synchronization with the horizontal synchronizing signal (may be referred to as a latch signal Ls).
The source driver
902
sends the analog voltage for gradation display-use (the voltage for gradation display-use) that is a resultant of the D/A conversion to an associated source signal line
1004
(see
FIG. 10
) provided in the liquid crystal panel
901
via the liquid crystal driving voltage output terminal.
The following description deals with the structure of the liquid crystal panel
901
with reference to FIG.
10
. The liquid crystal panel
901
is provided with pixel electrodes
1001
, pixel capacitor
1002
, TFTs
1003
acting as switching device that carry out ON/OFF the voltages applied to the respective pixels, source lines
1004
, gate signal lines
1005
, and an opposite electrode
1006
of the liquid crystal panel (corresponding to the opposite electrode
906
shown in FIG.
9
). Note that the area indicated as “A” corresponds to a single pixel in FIG.
10
.
The voltage for gradation display-use having the amplitude that varies depending on the brightness displayed in each target pixel is supplied to the source line
1004
from the source driver
902
shown in FIG.
9
. Scanning signals are applied to the respective gate signal lines
1005
from the gate driver
903
shown in
FIG. 9
so that a plurality of TFTs
1003
, that are provided in a longitudinal direction (i.e., in a direction in which the source signal lines
1004
are extended) are successively turned ON.
In the case where a TFT
1003
is turned ON, when a pixel electrode
1001
connected with the drain of such a TFT
1003
receives the voltage for gradation display-use from the source signal line
1004
, electric charges are stored (charged) in the pixel capacitor
1002
formed between the pixel electrode
1001
and the opposite electrode
1006
. Then, when the selection by the gate signal lines
1005
is completed and the TFT
1003
changes into an OFF (non-selection) state, the voltages that have been written into the pixel capacitor
1002
are maintained. The ON/OFF operation causes the light transmittance of the respective display unit elements (pixels) to change in accordance with the level of the voltage for gradation display-use that has been written into each pixel. This allows to realizing a target gradation display.
FIGS. 11 and 12
show an example of the waveform of the liquid crystal driving voltage to be applied to the source signal line
1004
, the gate signal line
1005
, and the pixel electrode
1001
shown in
FIG. 10
, respectively. In
FIGS. 11 and 12
, reference numerals
1101
and
1201
show the waveform of the voltage for gradation display-use outputted from the source driver
902
to the source signal line
1004
. In
FIGS. 11 and 12
, reference numerals
1102
and
1202
show the waveform of the scanning signal, for controlling of ON/OFF of the TFT
1003
, that is outputted from the gate driver
903
to the gate signal line
1005
. Note that when the reference numeral
1102
or
1202
is a high level, the TFT
1003
is in an ON state, and when a low level, the TFT
1003
is in an OFF state.
In
FIGS. 11 and 12
, reference numerals
1103
and
1203
show the electrical potential (voltage) of the opposite electrode
1006
(see FIG.
10
), and
1104
and
1204
show the waveform of the voltage to be applied to the pixel electrode
1001
. The change (see
FIG. 11
, for example) in the waveform of the voltage to be applied to the pixel electrode
1001
is explained by the fact that the voltage level corresponding to the electric charges charged in the pixel capacitor
1002
during the period of time in which (a) the TFT
1003
is turned ON when the scanning signal
1102
is a high level, this causes that the pixel capacitor
1002
starts to be charged (i.e., the voltage
1101
for gradation display-use is written), (b) the scanning signal is a low level so that the TFT
1003
is turned OFF, when the voltage across the pixel capacitor
1002
reaches a predetermined voltage level, and (c) thereafter, the scanning signal becomes a high level again. Note that the similar description is made with respect to the voltage of the waveform indicated as the reference numeral
1204
shown in FIG.
12
.
Note that the voltage to be applied to the liquid crystal material (not shown) is equal to the difference of electric potentials (voltage difference) between the pixel electrode
1001
and the opposite electrode
1006
(see the oblique lines shown in FIGS.
11
and
12
Alphonse Fritz
Birch & Stewart Kolasch & Birch, LLP
Saras Steven
Sharp Kabushiki Kaisha
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