Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-07-27
2002-06-11
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S067000, C345S068000, C345S069000, C345S070000, C315S169100
Reexamination Certificate
active
06404411
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a discharge type display technology, for example, to a display technique of plasma display panel to be introduced, to a display apparatus of personal computer and workstation or to a flat type wall-mounted television receiver, and moreover, relates to a technique of advertisement and information display apparatus or the like.
2. Description of the Related Art
A plasma display apparatus, for example, realizes display of physically thinner structure in place of display of the physically thick structure such as existing CRT system, and it is particularly expected as a large size display system.
For example, in the plasma display apparatus, one field (a sheet of display image) is divided into a plurality of subfields for every luminance and ultraviolet ray is generated by discharge for every pixel (display cell) to excite phosphor for the purpose of light emission. This discharge is called a sustain discharge and half tone is displayed by changing the number of times of this discharge for every subfield. In such a plasma display apparatus, since the electric charge particles accumulated in the discharge area (display cell) are eliminated (controlled) first in the first reset period of each subfield in order to display an image of one field (a sheet of display image), the reset pulse is impressed to the entire part of display screen (all cells) to generate the write discharge and self erasing discharge. After the reset period, the cells to be displayed by light emission is selected (addressed) on the display screen by utilizing the period called the address period before the sustain discharge explained above. Namely, the scan pulse is impressed to the scan electrode comprising, for example, of Y electrode and the address pulse is impressed to the address electrode which are arranged on the display screen.
As explained above, in the plasma display panel, the cells for display on the display screen are selected by impressing the scan pulse to the address electrode comprising Y electrode and thereafter an image is displayed by conducting sustain discharge on these selected cells.
At the beginning of each subfield, the write discharge and erase discharge have been conducted for the entire surface to erase the charged particles accumulated in the discharge area (display cells) without relation to whether the sustain discharge is conducted or not on the immediately preceding subfield. However, since light emission by such discharges occurs on all cells, luminance of black level rises particularly, resulting in deterioration of contrast. Therefore, for example, the Japanese Unexamined Patent Publication No. Hei 8-278766 describes the technique to erase the charges (wall charges) of only the cells in which the sustain discharge is performed in the immediately preceding subfield. This technique is intended to realize selective write discharge and self erase discharge of only the cells in which such sustain discharge is performed in the immediately preceding subfield in view of preventing deterioration of contrast. Even in this technique, the write discharge and erase discharge are performed for the entire surface to erase charges accumulated in the cells in the reset period of the first subfield of a plurality of subfields forming one field (a sheet of display image).
However, in the related technique explained above, intervals between adjacent upper and lower display cells and right and left lower display cells is narrowed particularly with miniaturization of cell structure requested by improvement for high definition of plasma display panel. Therefore, influence (so-called crosstalk) on the adjacent upper and lower cells and right and left cells due to the charges generated at the time of discharge of each cell becomes large. There arises a problem that it is difficult for each cell to perform normal operation, namely unwanted light emission by erroneous discharge and non-lighting of required cells are generated.
The Japanese Unexamined Patent Publication No. Hei 8-278766 certain discloses that the write discharge and erase discharge are performed selectively at the cells where the sustain discharge explained above is performed. However, in this related art, charges are perfectly erased, not considering that charges generated by self erase discharge are utilized in order to stabilize the next discharge.
SUMMARY OF THE INVENTION
The inventors of the present invention have confirmed by experiments that influence on the upper and lower neighboring display cells by the generated charges tends to become larger as fluctuation of time lag of discharge at the time of the bulk reset discharge becomes larger. When time lag of discharge becomes larger, normal address discharge can no longer be conducted during the address period following this reset discharge and thereby displayed image quality is deteriorated. Moreover, the inventors have also confirmed that influence on the right and left neighboring display cells is caused by erroneous discharge due to the crosstalk when the address discharge is generated. The displayed image quality by such erroneous discharge is deteriorated.
The present invention has been proposed by the inventors who have recognized a problem that displayed image quality is deteriorated due to non-uniform time lag of discharge when bulk reset discharge is conducted. In more practical, it is an object of the present invention to provide display technique for providing high quality display image on the high definition display screen by realizing stable address discharge through control of non-uniform time lag of discharge when the bulk reset discharge is generated in order to reduce crosstalk as the influence applied on the upper and lower neighboring cells. Moreover, the displayed image quality is deteriorated by erroneous discharge by the crosstalk generated when the address discharge is conducted. It is also an object of the present invention to provide display technique for providing high definition display screen and high quality display image. That is implemented by realizing stable address discharge through impression of voltage to accumulate charges in the polarity different from that of the voltage. The voltage is impressed when address discharge is conducted after the reset discharge in order to reduce erroneous discharge by the crosstalk in the left and right neighboring display cells.
Moreover, it is another object of the present invention to provide display technique for preventing deterioration of contrast by preventing erroneous discharge due to impression of scan pulse.
In order to attain the objects explained above, the present invention assures that:
(1) a discharge type display apparatus for displaying images on the display panel by selecting the cells for display discharge after the reset operation is provided with the structure that the pulse to conduct the preliminary process for selection is impressed to the electrode of cells during the period before the selection after impression of the first reset pulse;
(2) a display panel driving method for displaying images on the display panel using the subfields comprises the step of conducting the address operation to select the cells for display discharge after conducting the reset operation by impressing a plurality of reset pulses in every subfield to the electrode of cells during the subfield period for conducting the reset operation;
(3) a plurality of reset pulses are impressed to the same electrode in the item (2);
(4) in item (3), a couple of reset pulses are impressed and the second reset pulse is impressed within the period of 1 &mgr;s to several tens &mgr;s after completion of the first reset pulse;
(5) a plurality of reset pulses are impressed to different electrodes in item (2);
(6) in item (2), the end of impression of the first reset pulse among a plurality of reset pulses is almost matched with the start of impression of the next reset pulse;
(7) a discharge type display apparatus for displaying images on the d
Ishigaki Masaji
Masuda Takeo
Ohtaka Hiroshi
Sasaki Takashi
Hitachi Limited
Hjerpe Richard
Lesperance Jean
Mattingly Stanger & Malur, P.C.
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