Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-02-08
2004-09-07
Eisen, Alexander (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S204000
Reexamination Certificate
active
06788276
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 00-5731 filed Feb. 8, 2000 in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for controlling the drive power of a plasma display panel and a method therefor, and more particularly, to a method and apparatus which pre-estimates a load ratio, which is the ratio of the number of discharge cells to be display-discharged to the total number of discharge cells in the plasma display panel, on a frame-by-frame basis, and controls the number of display-discharge pulses in a corresponding frame so that the number of display-discharge pulses in the corresponding frame is inversely proportional to the preestimated load ratio.
2. Description of the Related Art
Since plasma display panels have high power consumption due to their drive characteristics, an apparatus for controlling power consumption depending on the load ratio of a frame to be displayed is greatly required.
Referring to
FIG. 1
, a driving apparatus of a typical plasma display panel
1
includes a controller
2
, an address driver
3
, an X driver
4
, and a Y driver
5
. The controller
2
generates drive control signals S
A
, S
Y
, and S
X
according to an incoming video signal. The address driver
3
processes an address signal S
A
from the controller
2
to generate a display data signal, and then applies the generated display data signal to address electrode lines. The X driver
4
processes an X drive control signal S
X
from the controller
2
to apply the processed X drive control signal S
X
to X electrode lines. The Y driver
5
processes a Y drive control signal S
Y
to apply the processed Y drive control signal S
Y
to Y electrode lines.
FIG. 2
shows the internal configuration of the controller
2
in the apparatus of FIG.
1
. Referring to
FIG. 2
, the controller
2
includes a subfield generator
21
, a power controller
22
, a subfield matrix
23
, a frame memory
24
, a memory interface
25
, a rearranger
26
, a timing signal generator
27
, XY switches
28
, and a memory
29
. The subfield generator
21
converts input video data signals red (R), green (G) and blue (B) to gray-scale data signals. The subfield matrix
23
classifies the gray-scale data signals based on the type of gray scales. The memory interface
25
stores the classified data signals from the subfield matrix
23
in the frame memory
24
, and inputs frame data from the frame memory
24
into the rearranger
26
. The rearranger
26
rearranges the frame data input through the memory interface
25
in such a way as to be well suited to a predetermined driving sequence, and outputs the address signal S
A
as the result thereof.
The timing signal generator
27
generates a timing signal according to an input horizontal synchronization signal H
SYNC
, a vertical synchronization signal V
SYNC
, a clock signal CLK, and a driving sequence permanently stored in the memory
29
such as a programmable read only memory (PROM). The XY switches
28
operate according to the predetermined driving sequence and switch the timing signal from the timing signal generator
27
to output the X drive control signal S
X
and the Y drive control signal S
Y
.
Here, the power controller
22
processes the input video data signals R, G, and B to preestimate a load ratio, which is the ratio of the number of discharge cells to be display-discharged to the number of discharge cells of the plasma display panel
1
, on a frame-by-frame basis, and to input a discharge number control signal APC to the timing signal generator
27
. The timing signal generator
27
then controls the number of display-discharge pulses in a corresponding frame in such a way as to be inversely proportional to the preestimated load ratio. The operation principle of the power controller
22
is based on a drive characteristic graph shown in FIG.
3
.
The drive characteristic graph of
FIG. 3
is obtained as follows. First, a load ratio versus electric power characteristic is obtained while changing the number Ns of display-discharge pulses in a frame. Then, load ratios L
4
, L
3
, L
2
and L
1
are equated to reference electric power values with respect to each of the number Ns of display-discharge pulses in a frame. In this case, a load ratio of 100% is set for the lowest number Ns (=500) of display-discharge pulses in a frame. Based on this principle, the following power control is performed depending on the load ratio, L
4
, L
3
, L
2
and L
1
.
The highest number Ns (=2,000) of display-discharge pulses in a frame is applied to the load ratio of 0 through L
4
. The next highest number Ns (=1,500) of display-discharge pulses in a frame is applied to the load ratio which is greater than L
4
and less than or equal to L
3
. The next highest number Ns (=1,000) of display-discharge pulses in a frames is applied to the load ratio which is greater than L
3
and less than or equal to L
2
. The lowest number (=500) Ns of display-discharge pulses in a frame is applied to the load ratio which is greater than L
2
. Here, the load ratio L
1
denotes a load ratio of 100% where all discharge cells perform display-discharge.
The cross points P
1
, P
2
, P
3
, and P
4
of the load ratio corresponding to the electric power are linked together to obtain a drive characteristic curve. The number Ns of display-discharge pulses in a frame and the load ratio can be appropriately selected within a range not deviating from the thus-obtained drive characteristic.
FIG. 4
shows the internal configuration of a conventional power controller. Referring to
FIG. 4
, the conventional power controller includes a load ratio preestimator
41
, a low pass filter (LPF)
42
, and a discharge number controller
43
. The load ratio preestimator
41
preestimates a load ratio, which is the ratio of the number of discharge cells to be display-discharged to the total number of discharge cells in a plasma display panel, by a frame-by-frame basis. The LPF
42
works such that the level of an output signal from the load ratio preestimator
41
does not rapidly change. The discharge number controller
43
outputs a discharge number control signal APC corresponding to the load ratio signal from the LPF
42
.
Here, if a level of an output signal from the load ratio preestimator
41
rapidly changes, for example, if the load ratio drops from 95% to 10%, the number Ns of display-discharge pulses in a frame rapidly changes accordingly by the discharge number controller
43
. The LPF serves to prevent an electric shock of a system due to the rapid change. However, since the control of the discharge number controller
43
is always delayed by a predetermined time by the LPF
42
, where a quickly moving object is displayed on a screen, power consumption increases at the point where this delay occurs. Thus, a speed of changing the display-discharge number per frame is always continuous. In other words, a transition time for changing the display-discharge number is always continuous according to the prior art. Thus, the control of the discharge number controller is inaccurate during the transition time. Where a quickly moving object is displayed, the average range for changing the display discharge number is relatively increased, so that the control of the discharge number controller is more inaccurate during the transition time. Thereby, according to the prior art, power consumption in a plasma display panel can increase more during the transition time.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide an apparatus which controls the drive power of a plasma display panel that maintains constant power consumption without imposing electrical shock on a system.
It is also an object of the present invention to provide a method of controlling the drive power of a plasma display panel that maintains constant power consumption
Eisen Alexander
McGuireWoods LLP
Samsung SDI & Co., Ltd.
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