Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-11-05
2002-12-24
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S077000
Reexamination Certificate
active
06498593
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is related to Japanese patent application No. HEI 11(1999)-120087 filed on Apr. 27, 1999 whose priority is claimed under 35 USC §119, the disclosure of which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display panel (“PDP”) and a driving method of the same. More particularly, the invention relates to a plasma display panel having multiple built-in discharge cells as formed at locations partitioned by barrier walls or ribs in a discharge space within a panel, and also to a driving method thereof.
2. Description of the Related Art
Currently available PDPs are thin flat-panel display devices with enhanced on-screen image visibility and high-speed displayability while offering large-screen attainability. One example of such devices is an active-matrix driven areal-dischargeable PDP unit, which is typically arranged so that display electrodes forming a pair upon application of a drive voltage are laid out on the same substrate. The active-matrix PDP of this type is preferably adaptable for use in displaying full-color images by means of fluorescent materials.
One typical known AC-driven color PDP of the areal discharge type is designed in a way which follows. Multiple pairs of main electrodes for use in producing an areal discharge are horizontally disposed in substantially parallel to one another on one of spatially laminated substrates making up a panel at a pre-specified interval or pitch of reverse slit (non-discharge region) while providing on the remaining substrate a plurality of address (signal) electrodes used for address discharge production and multiple stripe-shaped ribs for physically partitioning a discharge space, adjacent ones of which sandwiches a corresponding one of the address electrodes therebetween, in substantially parallel in the vertical direction (a direction transverse to the main electrodes), wherein fluorescent layers of the three primary colors—here, red (R), green (G), and blue (B)—are formed in a narrow elongate groove between adjacent ones of the ribs.
Note here that the areal discharge is sometimes called a “display discharge” in view of the fact that such discharge is a main discharge for image display and may also be called a “sustain discharge” because of the fact that it is a turn-on retaining discharge after addressing. Additionally, the main electrodes for areal discharge production are called “display electrodes” since these are display discharging electrodes, or alternatively are called “sustain electrodes” as they are the electrodes for use in producing the sustain discharge.
An on-screen image displaying operation of the PDP of this type is as follows. One sustain electrode of a sustain electrode pair is used as a scanning electrode to sequentially apply a voltage while during such voltage application applying a voltage to a desired address electrode causing an address discharge to take place between the address electrode and the one sustain electrode to thereby select a discharge cell to be turned on (this is generally referred to as “addressing”). Thereafter, by utilizing wall charge as has been formed during addressing, let a sustain discharge occur between paired sustain electrodes for an appropriate number of times that adequately complies with the intended luminance and color shade levels (thereby causing the discharge cell to turn on). To be brief, in case where one pixel consists of three separate RGB discharge cells, any desired color shade is reproducible by suitably determining what color of discharge cell is selected from RGB and how many times such cell is to be turned on; in this respect, the related art PDP is designed to produce the sustain discharge for a specified number of times as required to attain such reproducibility.
This gradation-of-shading displayability (color reproducibility) based on the control of the discharging number of such sustain discharge is typically attained by a method as will be discussed below. Subdivide a single frame (or a single field if one frame consists of two fields) into eight separate subfields, which are then subjected to weighting processing so that a relative ratio of these subfields' luminance intensities becomes 1:2:4:8:16:32:64:128 for setting up the number of sustain discharge occurrences of each subfield. This makes it possible to perform brightness setup of 256 different levels with respect to each of the RGB colors, which leads to on-screen displayability of 256
3
kinds of possible colors.
Incidentally, currently available PDPs suffer from a physical limitation as to shrinking or “downsizing” of electrodes and ribs; due to this, the existing PDPs are encountered with a problem as to image quality reduction (low resolution) when employed for small-size screen displays when compared to traditional cathode-ray tube (CRT) display units, although the PDPs are adaptable for use with large-screen displays. To avoid this problem, several technical approaches to maximizing the required number of pixels (discharge cells) while minimizing requisite electrodes in number are proposed in recent years. One typical approach to achieving such maximal-pixel/minimal-electrode configuration is to employ a specific technique called an “alternate lighting of surfaces (ALiS)” scheme for use with AC-driven color PDPs of the areal discharge type.
This scheme is a technique which replaces the one as has been designed to use two separate sustain electrodes per display line to visually display an image and which realigns such sustain electrodes at the equal pitch to utilize those available spaces between all the sustain electrodes as display lines. With this scheme, as shown in
FIGS. 10A
,
10
B and
10
C, one frame is subdivided into two fields consisting of an odd-numbered field and an even-numbered field for causing in the odd-numbered field a sustain discharge to take place at an odd-numbered line between sustain electrodes X
n
, Y
n
(where “n” is a given natural number) (see
FIG. 10A
) while producing in the even-numbered field a sustain discharge at an even-numbered line between sustain electrodes Y
n
, X
n+1
(see FIG.
10
B), wherein the odd-numbered and even-numbered lines are combined or synthesized together for constitution of a single on-screen image (see FIG.
10
C). In the drawings, a dot-matrix display pattern of an alphabetical letter “A” is shown by way of example. A reference character A is used in this drawing to designate the address electrodes. Accordingly, this scheme permits the above-noted reverse slit portion to be used as part of an effective displayable region, which doubly increases the display lines in number without having to increasing the requisite number of electrodes involved.
This ALiS scheme requires the use of a panel structure shown in FIG.
11
. More specifically, parallel sustain electrodes X
n
, Y
n
are disposed in the horizontal direction on a display plane while parallel address electrodes A are laid out at right angles thereto in the vertical direction on the display plane, wherein ribs
31
are arranged between the address electrodes A in a way parallel to the address electrodes A. The exact number of such sustain electrodes is determined so that it is equal to the number of those discharge cells aligned in the vertical direction (vertical cell number) plus one—that is, the number of the sustain electrodes disposed is the display line number (2i) plus 1 (where “i” is the maximum electrode pair number whereas the number of the address electrodes is the same as the number of those discharge cells in the horizontal direction (horizontal cell number).
The display lines include a first display line L
1
as defined between the sustain electrodes X
1
and Y
1
, a second display line L
2
between sustain electrodes Y
1
and X
2
, a third display line L
3
between sustain electrodes X
2
and Y
2
, a (2n−1)th display line L
2n−1
between sustain electrodes X
n
and Y
n
, and an n-th display
Fujimoto Sunao
Nakahara Hiroyuki
Fujitsu Limited
Patel Nitin
Shankar Vijay
Staas & Halsey , LLP
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