Computer graphics processing and selective visual display system – Plural physical display element control system – Segmented display elements
Reexamination Certificate
2001-01-04
2002-12-17
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Segmented display elements
C345S039000, C345S032000, C345S083000, C345S084000
Reexamination Certificate
active
06496162
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a full-color type light emitting diode display unit (hereinafter referred to simply as an “LED unit”), and more particularly to an LED display unit which is expanded in light distribution angle, and is increased in luminance while improving Quality of mixed colors and white balance.
2. Description of the Related Art
As a result of successful production of high luminance blue LEDs, it becomes possible to manufacture a full-color display unit wherein three primary colors of blue, red, and green are used. A large-sized display wherein such LED display units are used has been manufactured, and such a large-sized display is fixed to, for example, the wall of a building or the like, so that it attracts walkers' eyes. Meanwhile, high luminance of green LEDs has been also realized recently, whereby full-color display units became possible to be fabricated by the use of the same number of LEDs as those of red and blue LEDs. In this connection, a larger number of green LEDs have been heretofore used than those of red and blue LEDs.
LED display unit is classified generally into the following two types.
(1) Large-sized Display
One dot is formed by utilizing a plurality of cannon ball-shaped LED lamps each having different luminescent colors, one module to display one Chinese character is composed by horizontally and vertically arranging 16×16 lamps (=256 dots), and a plurality of the modules are horizontally and vertically arranged. The resulting large-sized display is principally employed for display of information on the wall of a building or along an express-highway.
(2) Small- to Medium-sized Display
One dot of a cannon ball-shaped LED lamp is formed by employing a plurality of LED chips each having different luminescent color, one module is composed by horizontally and vertically arranging 16×16 lamps (=256 dots), and a plurality of the modules are horizontally and vertically arranged. The small- to medium-sized display is principally employed for display of information on schedules in a train station yard.
In such a full-color type LED display unit as described above, a plurality of LED chips or a plurality of LED lamps each having different luminescent color are used for pixels, so that the following characteristics are required.
(1) Excellent quality of mixed colors
(2) Excellent white balance
(3) Wide light distribution angle
(4) High luminance
FIGS. 1A and 1B
show a cannon ball-shaped LED wherein a plurality of the LED chips are used. The LED lamp
4
is one employed principally for a small-to medium-sized display, and made from a resin which is added with a light diffusing material. The LED lamp
4
comprises a lens
40
for sealing three LED chips
20
G (green),
20
R (red), and
20
B (blue); and leads
41
for connecting the LED chips
20
G,
20
R, and
20
B to wiring patterns of a printed-circuit board.
FIG. 2
shows an LED display unit in which the LED lamps
4
are used to be arranged in matrix. The LED display unit is constituted by horizontally and vertically arranging 16×16 LED lamps
4
(=256 dots) on a printed-circuit board
10
. In this LED display unit, for preventing short circuit of wiring patterns on the printed-circuit board caused by close arrangement of leads of the LED lamps
4
on the printed-circuit board, the LED chips
20
G,
20
R, and
20
B are obliquely arranged to widen the interval of the leads
41
of the LED lamp
FIG. 3
is a graphical representation showing results obtained by measuring light distribution angle of the LED display unit in the A—A direction in
FIG. 2
, wherein the abscissa indicates the light distribution angle, and the ordinate indicates relative luminance based on the maximum luminance of 1. As is apparent from the figure, all the three colors have a relative luminance of ½ or more in the region “a”, and at least one of the colors has a relative luminance of ½ or more in the regions “b
1
” and “b
2
”. On the other hand, all the three colors have a relative luminance of {fraction (1/10 )} or more in the region “c”. From the above results, the contents displayed on the LED display unit can be viewed in the range “c” of approximate 90°.
In the conventional LED display unit, howevers, there arises color collapse, and particularly, luminance of green is low in the region “b
1
”, while it is high in the region “b
2
”, so that sufficient white balance cannot be obtained, since three colors of LED chips have been obliquely arranged. Furthermore, although red color is hard to mix with either blue color or green color, the relative luminance of both blue and green is positioned on the upper and lower sides of the relative luminance of red color in the regions “b
1
” and “b
2
”, so that good quality of mixed colors cannot be obtained.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an LED display unit which is expanded in light distribution angle, and is increased in luminance while improving quality of mixed colors and white balance.
According to the first aspect of the invention, an LED display unit comprises: a plurality of light emitting diode (LED) pixels arranged in a predetermined pattern to display a predetermined image;
each of the plurality of LED pixels, comprising: a green LED, a red LED, and a blue LED vertically arranged in a row, such that the green LED is above the red LED, and the blue LED is below the red LED.
According to the second aspect of the invention, an LED display unit, comprises: an insulation substrate provided with a plurality of cavities defined in a predetermined pattern on one surface thereof, a reflection surface being formed on an inner wall in each of the plurality of cavities: and
a plurality of light emitting diode (LED) pixels positioned in the plurality of cavities to display a predetermined image;
each of the plurality of LED pixels, comprising: a green LED, a red LED, and a blue LED vertically arranged in a row, such that the green LED is above the red LED, and the blue LED is below the red LED.
REFERENCES:
patent: 4271408 (1981-06-01), Teshima et al.
patent: 4628422 (1986-12-01), Ewald
patent: 5140220 (1992-08-01), Hasegawa
patent: 5144288 (1992-09-01), Hamada et al.
patent: 5583351 (1996-12-01), Brown et al.
patent: 5812105 (1998-09-01), Ven
patent: 5894196 (1999-04-01), McDermott
patent: 6177761 (2001-01-01), Pelka et al.
patent: 6236382 (2001-05-01), Kawakami et al.
Kawakami Shingo
Mizutani Junichi
Mori Hideki
Katten Muchin Zavis & Rosenman
Koha Co., Ltd.
Kovalick Vincent E.
Shalwala Bipin
LandOfFree
Light emitting diode display unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light emitting diode display unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light emitting diode display unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2952900