Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-09-10
2003-05-06
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C345S055000, C345S204000, C345S214000
Reexamination Certificate
active
06559603
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an driving apparatus for driving a flat display panel such as an AC drive type plasma or an electroluminescence display panel.
2. Description of the Related Art
There have been developed a flat display panel constituted by capacitive light-emitting elements such as plasma display panel (PDP) or electroluminescence diaply panel (ELP).
FIG. 1
shows a general structure of a plasma display apparatus including a PDP as such flat panel.
In
FIG. 1
, a PDP
10
includes row electrodes Y
1
through Y
n
and X
1
through X
n
the corresponding ones of which constitute row electrode pairs each corresponding to each one of 1
st
to n-th rows of a single frame or screen. The PDP further includes column electrodes Z
1
through Zm respectively corresponding to the 1
st
to m-th columns of the single frame. The column electrodes Z intersect the row electrode pairs X and Y and sandwich dielectric layers (not shown) and discharge cavities (not shown) together with the row electrode pairs X and Y so that a discharge cell is formed at each intersection between one pair (X, Y) of the row electrode pairs and one of the column electrode Z.
In this instance, it is to be understood that each of the discharge cells takes either one of two states of “light-emitting” and “non-light-emitting”. In other words, the discharge cell can display merely two gradations of the lowest brightness (non-light-emitting state) and of the highest brightness (light-emitting state).
A drive apparatus
100
for driving the PDP
10
therefore employs the so-called sub-field method in driving the PDP
10
so as to realize an intermediate gradation of brightness in response to an input video signal.
In the sub-filed method, each picture element carried by the input video signal is converted into a video data of N bits. One field or frame of contained by the video signal is divided into N pieces of sub-fields the respective sub-fields correspond to the respective digits of one of the video data. An appropriate number of discharge times is allotted to a sub-field in accordance with a weight given to the sub-field. The respective discharge cavities are triggered so as to initiate the discharge action so as to constitute the respective sub-fields. Each picture element takes a brightness of an intermediate gradation corresponding to a sum of the respective number of discharge times each having occurred within the respective sub-fields within one field or frame.
A selective erasure address method is known as an example of the method for actually driving the PDP by using the subfield method described above.
FIG. 2
is a diagram showing timings of the application of various driving pulses which are applied to the column electrodes and row electrodes of the PDP
10
by the driver
100
in a subfield when the gray-scale drive is performed based on the selective erasure address method.
First, the driver
100
applies reset pulses RP
X
having a negative polarity simultaneously to the respective row electrodes X
1
through X
n
and applies reset pulses RP
Y
having a positive polarity simultaneously to the respective row electrodes Y
1
through Y
n
(simultaneous resetting step Rc).
In accordance with application of the reset pulses RP
X
and RP
Y
, all of the discharge cells of PDP
10
are discharged to reset, and a predetermined amount of wall charge is uniformly formed in the respective discharge cells.
By this process, all of the discharge cells in PDP
10
are initialized to a “light emitting cell” state.
Next, the driver
100
converts the incoming video signal to pixel data of 8 bits, for example. The driver
100
separates respective bits of the 8 bit pixel data for each of the bit digits, to obtain pixel data bits, and generates pixel data pulses having a pulse voltage in accordance with the logical level (or value) of the corresponding bit. For example, the driver
100
generates a pixel data pulse DP which has a high voltage when logical level of the pixel data bit mentioned above is “1” and a low voltage (0 volt) when the logical level of the pixel data bit is “0”. Further, as shown in
FIG. 2
the driver
100
applies to the column electrodes Z
1
through Z
m
successively each of m groups of pixel data pulses DP
11-1m
, DP
21-2m
, DP
31-3m
, . . . DP
n1-nm
which are formed by grouping the pixel data pulses DP
11
-DP
nm
of one screen (n rows and m columns) for each of display lines (m lines). Furthermore, the driver
100
generates a scan pulse SP as shown in
FIG. 2
in synchronism with an application timing of each of the respective pixel data pulse group DP and applies it successively to the row electrodes Y
1
through Y
n
(pixel data writing process Wc). With this operation, there causes discharge (selective erasure discharge) only at the discharge cell at an intersecting portion of a “row” applied with the scan pulse SP and “column” applied with the pixel data pulse having high voltage, so that wall charge which has been remaining in the discharge cell is selectively erased. With this process, the discharge cells which have been initialized to the “light emitting cell” state in the simultaneous resetting step mentioned above is shifted to a “no light emitting cell” state. Meanwhile, the selective erasure discharge is not caused in the discharge cells formed to cross the “rows” and “columns” in which the pixel data pulse having low voltage is applied while the scan pulse SP is applied, and the state of being initialized at the simultaneous resetting step Rc, that is, the state of “light emitting cell” is maintained.
Next, the driver
100
repetitively applies sustaining pulses IP
X
having a positive polarity as shown in
FIG. 2
to the row electrodes X
1
through X
n
, and repetitively applies sustaining pulses IP
Y
having a positive polarity as shown in
FIG. 2
to the row electrodes Y
1
through Y
n
in the periods when the sustaining pulses IP
X
is not applied (light emission sustaining step Ic).
In this process, only the discharge cell at which wall charge is kept remaining, that is, the discharge cell brought into the “light emitting cell” state, carries out a discharge (sustaining discharge) each time the sustaining pulses IP
X
and IP
Y
are applied alternately. That is, only the discharge cell set to the “light emitting cell” state in the pixel data writing step Wc mentioned above, repeats the light emission in accordance with sustaining discharge to the number of times corresponding to the weight of the respective subfield, and maintains the light emitting state. The number of times of the application of the sustaining pulses IP
X
and IP
Y
is previously set in accordance with the weight of the respective subfield.
Then, the driver
100
applies an erasure pulse EP as shown in
FIG. 2
to the row electrodes X
1
to X
n
(erasing step E). With this step, erasing discharge takes place simultaneously in all of the discharge cells, to extinguish the wall charge which has been remaining in each discharge cell.
An intermediate brightness corresponding to a video signal is obtained visually, by repeating the sequence of steps described above in a plurality of number of times in one field.
However, in the case of capacitive display panels such as a PDP and ELP, with regard to the pixel data pulses which are applied to the column electrodes in order to write the pixel data, each time the data of each row is written the charge and discharge must be executed also in other rows in which the writing of data is not performed. Furthermore, capacitive charge and discharge between neighboring column electrodes must also be performed. Therefore, a problem has been encountered that the electric consumption during the writing of pixel data is large.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a drive apparatus of a display panel which is able to reduce the electric power consumed during the writing of pixel data.
The drive apparatus of a display panel according to the present invention
Alemu Ephrem
Philogene Haissa
Pioneer Corporation
LandOfFree
Driving apparatus for driving display panel 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 for driving display panel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving apparatus for driving display panel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3008809