Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
1999-03-26
2001-11-13
Nguyen, Chanh (Department: 2675)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S083000
Reexamination Certificate
active
06317138
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video display device suitable for application to a large video display device or the like. Specifically, the present invention relates to a video display device wherein a memory stores previously current correction values for correcting variations in luminous brightness of a plurality of display elements constituting a video display part, and the variations in luminous brightness within the video display part can be corrected by driving the display elements through the use of the current correction values read from the memory.
2. Description of Related Art
A large video display device has been set up in a place for doing various events outdoors, an outdoor or indoor stadium, sport facilities, and so forth. The large video display device displays the contents of events, the results of competition, and so forth on a large-sized video display part (i.e., a panel or a screen) thereof.
The video display device for this purpose has a video source (i.e., a VTR or the like)
12
, as shown in FIG.
1
. The video source
12
transmits video images (the contents of events, the contents of competition, drama programs, and so forth) to a signal processing device
30
where they are converted into signal form suitable for a video display part
14
. Thereafter, the signal processing device
30
transmits the converted signal to the video display part
14
and then a desired image or picture is displayed on the video display part
14
. The video display part
14
is constructed so as to be suitable for a large screen (e.g., 4m×3m).
The video display part
14
is a collection of a plurality of dots.
FIGS. 2A through 2C
show an example thereof. In the example, a unit dot (hereinafter called “dot”)
16
comprises a trio of display elements, each of which emits light of red R, green G or blue B, as shown in FIG.
2
A. The dots
16
are arranged over p rows and q columns (both p and q are four in the illustrated example) to form each individual unit cell
18
(see FIG.
2
B). Further, the unit cells are arranged over m rows and n columns (both m and n are four in the illustrated example) to form a display unit
20
as a unit (see FIG.
2
C). A large video display part
14
is constructed by a collection of the display units
20
.
In such a video display part
14
, separate drivers drive respectively the display elements themselves defined as an RGB trio constituting the dot
16
in order to obtain sufficient luminous brightness, for example. The unit cell
18
is normally formed by 16 dots (4×4 dots) and thus forty eight individual drivers drive forty eight display elements (16 dots×3 elements).
Even if each unit cell is represented as 4×4=16 dots as shown in
FIG. 3
, forty eight drivers corresponding to forty eight display elements cause a drive circuit to increase in size. As means for solving this, means have been proposed for reducing the number of drivers to ½ of the number by providing switching or selector means such that one driver drives two display elements.
FIG. 4
is a fragmentary systematic diagram showing one example of the proposal. When one unit cell consists of forty eight display elements as shown in
FIG. 3
, a driver circuit
32
is constructed so as to drive twenty-four display elements corresponding to ½ of the forty eight display elements. Thus, the driver circuit (IC driver)
32
comprises latch circuits
33
a
through
33
x
for latching twenty for video data S
0
through S
23
and drivers
34
a
through
34
x
electrically connected to the latch circuits at their subsequent stages as shown in FIG.
4
. Each of the respective drivers
34
a
through
34
x
is respectively connected to their corresponding display elements RU
0
through BL
7
via switching means
35
and then the driver circuit
32
transmits the outputs of drivers
34
a
through
34
x
to the display elements RU
0
through BL
7
.
In the unit cell as shown in
FIG. 3
, eight dots of an n row and an n+2 row (i.e., a lower-stage dot group L) are simultaneously driven. Next, eight dots of the remaining n+1 row and n+3 row (lower-stage dot group L) are also simultaneously driven. That is, these dot groups, i.e., display element groups U and L, are alternately driven in a predetermined cycle. Here, each set of the display elements RU
0
through RU
7
, GU
0
through GU
7
and BU
0
through BU
7
emits respectively the same light-emitting color. Similarly, each set of the display elements RL
0
through RL
7
, GL
0
through GL
7
and BL
0
through BL
7
emits respectively the same light-emitting color.
An example of the alternate driving of the dot groups U and L will be shown in
FIGS. 5A through 5C
. These figures show the case in which they are alternately switched over plural times (about 16 times) at time intervals (each corresponding to {fraction (1/30)} second) of individual one frame. During this period of time for one frame, the same video data is supplied to the corresponding display element group.
On the other hand, when the video display part
14
comprises the plurality of display elements, as described above, such as light-emitting diode devices (LEDs) the luminous brightness of each individual element varies, although dissimilar even according to the display element to be used. It is therefore necessary to correct previously current values for driving the display elements so that all the display elements to be used may be kept constant in luminous brightness.
As a current correcting method, adjustment of constants of the drivers for driving display elements is considered. In doing so, however, when a unit cell is replaced by another, the corresponding individual drivers must be re-adjusted so as to provide new current correction values for display elements provided within the replaced unit cell. This becomes so troublesome.
With the foregoing problems in view, it is therefore an object of the present invention to provide a video display device capable of easily setting current correction values for adjusting luminous brightness even when a unit cell is replaced by another.
SUMMARY OF THE INVENTION
According to one aspect of this invention, for achieving the above object, there is provided a video display device comprising a display unit including a unit cell which is comprised of a plurality of dots arranged vertically and horizontally, each dot being comprised of a plurality of display elements; first memory means for storing therein video data to be supplied to the plurality of display elements; and second memory means for storing therein correction data for correcting variations in luminous brightness of each of the display elements; wherein the display elements are driven based on the correction data read from the second memory means.
In the present invention, the correction data (i.e., current correction values) for correcting the variations in luminous brightness of each display element, is stored in the second memory means. When the display elements are driven, they are driven based on the current correction values related to them. Thus, the plurality of display elements emit light at the same brightness level. When the brightness of a specific unit cell is re-adjusted in the case that, for example, the unit cell is replaced by another, the correction data relating to the unit cell is updated. In doing so, the entire brightness of the video display part can be held uniform even when any unit cell is replaced by another.
The display element groups are alternately driven using the same video data of one frame. Further, since the data stored in the first memory means is simply read out as the video data in this case, the video data can be processed at high speed.
Typical ones of various inventions of the present inventions have been shown in brief. However, the various inventions of the present application and specific configurations of these inventions will be understood from the following description.
REFERENCES:
patent: 4581655 (1986-04-01), I
Okamoto Eizo
Yano Motoyasu
Anyaso Uchendu O.
Kananen Ronald P.
Nguyen Chanh
Rader Fishman & Grauer
Sony Corporation
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