Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-04-04
2004-12-14
Bella, Matthew C. (Department: 2676)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S076000, C345S087000, C345S067000, C345S036000, C345S050000, C345S088000
Reexamination Certificate
active
06831627
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving method for a liquid crystal display which is suitable for a thin display, in particular, to a driving method for a liquid crystal display wherein deterioration of the image quality, such as unclearness of an outline and blurring of colors when displaying a moving image, is prevented so as to increase an image quality and a luminance.
2. Description of the Related Art
A liquid crystal display is provided with two sheets of glass substrate and a liquid crystal layer placed between them. In general, in a thin film transistor (TFT) type panel, color filters for three colors (red, green and blue) are formed on the glass substrate on the side opposite to the TFT side glass substrate where TFTs are provided.
FIG. 1
is a cross section view showing a structure of a liquid crystal display according to a prior art.
FIG. 2
is a block diagram showing a structure of the liquid crystal display according to the prior art.
In the liquid crystal display according to the prior art, a TFT portion
102
is provided on the surface of a glass substrate
101
. The TFT portion
102
is provided with a plurality of scanning electrodes (not shown) arranged parallel to each other, a plurality of signal electrodes arranged so as to cross those scanning electrodes, and TFTs as switching elements arranged at intersections between the scanning electrodes and the signal electrodes. Accordingly, the TFTs are arranged in a matrix form. On the other hand, a polarizing plate
103
is attached to the back surface of the glass substrate
101
. Here, the scanning electrodes extend in the horizontal direction while the signal electrodes extend in the vertical direction.
In addition, a glass substrate
104
is provided in parallel with the glass substrate
101
, with a proper space between them, on the side of the TFT portion
102
of the glass substrate
101
. A common electrode layer
105
made of a transparent conductive material and color filters
106
are provided on the surface of the glass substrate
104
opposite to the glass substrate
101
. As for the color filters
106
, three color types of filters, that is to say, red filters
106
R, green filters
106
G, and blue filters
106
B, which extend in the vertical direction are provided and are arranged so as to repeat, in order, in the horizontal direction. The color filters
106
are formed by applying pigments or dyes. Here, each pitch of the filters
106
R,
106
G and
106
B coincides with the pitch of the signal electrodes. On the other hand, a polarizing plate
107
is attached to the back surface of the glass substrate
104
to the surface opposite to the glass substrate
101
.
Then, the glass substrate
101
, the glass substrate
104
and the like, are integrated so as to provide a liquid crystal layer
108
by injecting a liquid crystal material between them. In this manner, an active matrix type liquid crystal display panel (LCD panel)
110
is configured.
In addition, a light source
109
and a light guide plate
111
, which guides light emitted from this light source
109
so that it enters the liquid crystal display panel
110
in the vertical direction, are provided on the back surface of the glass substrate
101
. A reflecting sheet, a diffusion plate (not shown) and the like are provided between the light guide plate
111
and the LCD panel
110
. Then, a backlight is formed of the light source
109
, the light guide plate
111
and the like. As for the light source
109
, mainly a cathode ray tube fluorescent lamp is utilized.
In addition, a scanning circuit
131
, which drives n scanning electrodes G
1
to Gn, and a holding circuit
132
, which drives (m×3) signal electrodes, in total, DR
1
to DRm, DG
1
to DGm and DB
1
to DBm are provided in the liquid crystal display panel
110
. In addition, a signal processing portion
133
which processes image data and outputs the result to the scanning circuit
131
and the holding circuit
132
is provided. Moreover, a source for gradation
134
is provided which supplies voltage for the gradation display, to the holding circuit
132
, associated with the output signal of the signal processing portion
133
. Signals outputted from the signal processing portion
133
to the scanning circuit
131
are a clock signal and a start signal.
Next, a driving method for the liquid crystal display according to the prior art, which is configured as described above, is described.
FIG. 3
is a graph diagram showing the relationship between time, which is taken along the horizontal axis, and luminance, which is taken along the vertical axis, in the liquid crystal display according to the prior art. In
FIG. 3
, the two-dotted broken line shows luminance set for one pixel and the solid line shows the actual luminance for the one pixel.
In the driving method according to the prior art, scanning pulses are applied in sequence from the scanning electrode G
1
to the scanning electrode Gn by the scanning circuit
131
with reference to the start pulse V
SP
and the clock signal V
CLK
. Together with this, a voltage for gradation display is applied to the signal electrodes DR
1
to DRm, DG
1
to DGm and DB
1
to DBm by the holding circuit
132
.
However, since there exists a response time for the voltage applied to the liquid crystal until the full rotation is achieved, the actual luminance (solid line) cannot reach the set value immediately but, rather, rises gradually even when the voltage for gaining luminance (two-dotted broken line) is applied to a signal electrode as shown in FIG.
3
. In the case of scanning at 60 Hz, time required for the scanning of one frame is approximately 16.7 milliseconds while a response time of a twisted nematic (TN) type liquid crystal is approximately 15 milliseconds.
In addition, the backlight
109
is turned on at all times. Therefore, light of the three colors of red, green and blue is emitted from the liquid crystal display panel
110
simultaneously in accordance with the extent of the rotation of the liquid crystal.
In addition, the development of an organic electro-luminescence (EL) display as a thin type display is also progressing.
FIG. 4
is a schematic cross section view showing an EL element and its luminous principle and
FIG. 5
is a block diagram showing the structure of an organic EL display according to a prior art.
The EL element is configured as follows. That is to say, a transparent indium tin oxide (ITO) electrode
122
is formed as a positive electrode on a transparent substrate
121
made of glass or film. In addition, on the ITO electrode
122
, an organic positive hole injection layer
123
and an organic luminous layer
124
are deposited in sequence and, on top of that, a metal electrode
125
is formed as a negative electrode. Then, when a voltage is applied between the ITO electrode
122
and the metal electrode
125
, light is emitted from the organic luminous layer
124
to the side of the transparent substrate
121
.
The organic EL display is provided with a simple matrix system EL panel
120
where EL elements which are configured in the above manner are arranged in a matrix form. In addition, a row driving portion
135
which drives row electrodes R
1
to RL, which the number is the same as that of the scanning lines, and a column driving circuit
136
which drives (m×3) column electrodes, in total, CR
1
to CRm, CG
1
to CGm and CB
1
to CBm are provided. In the column driving circuit
136
, a latch circuit, which maintains the voltage based on the signal from a signal processing portion and which outputs signals for the number of column electrodes at the same time, and a constant current circuit, which converts the voltage outputted from this latch circuit into a current so as to supply it to a column electrode, are provided. In the organic EL display, a signal processing portion
137
which processes image data and which outputs the result to the row driving portion
135
and the column driving circuit
136
is further provided. Signals
Aoki Makoto
Hasegawa Fumio
Bella Matthew C.
Hayes & Soloway P.C.
NEC LCD Technologies Ltd.
Tran Tam
LandOfFree
Driving method for liquid crystal display 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 method for liquid crystal display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving method for liquid crystal display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3321153