Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
1998-10-30
2001-04-03
Patel, Ashok (Department: 2875)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S573000, C313S113000, C313S317000
Reexamination Certificate
active
06211612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to a cold cathode fluorescent display (CFD) and in particular, to a high luminance, high efficiency, long lifetime, monochrome or multi-color or full-color ultra-large screen display device, which can display character, graphic and video images for both indoor and outdoor applications.
2. Description of the Prior Art
The major prior technologies for ultra-large screen display are as follows:
A. Incandescent lamp display:
This display screen consists of a lot of incandescent lamps. The white lamps are always used for displaying a white and black character and graphic. The color incandescent lamps, which use red, green, and blue (R, G, B) color glass bubbles, are used for displaying multi-color or full-color character, graphic and image. An incandescent lamp display has been widely used for an outdoor character and graphic displays and possesses certain advantages such as high luminance, functionable at direct sunlight with shade and low cost of lamps. Nevertheless, this technology suffers from the following disadvantages: low luminous efficiency (i.e., white lamp about 10 lm/W; R, G, B<⅓ of white);
high power consumption; poor reliability, unexpected lamp failure; short lifetime; expensive maintenance cost; long response time and is unsuitable for video-display.
B. LED:
LED has been widely used for indoor large screen and ultra-large screen displays, to display a multi-color and full-color character, graphic and video image. This display is able to generate high luminance for indoor applications and can maintain a long operation lifetime at indoor display luminance level. The disadvantages of LED, however, are as follows: low luminous efficiency and high power consumption especially for the ultra-large screen display; low luminance for outdoor applications especially when a wide viewing angle is required or at direct sunlight; is expensive, especially for an ultra-large screen display because of of the need of a lot of LEDs; and has a lower lifetime at a high luminance level.
C. CRT:
CRT includes Flood-Beam CRT (e.g., Japan Display '92, p. 285, 1992), and matrix flat CRT (e.g., Sony's Jumbotron as disclosed in U.S. Pat. No. 5,191,259) and Mitsubishi's matrix flat CRT (e.g., SID '89 Digest, p. 102, 1989). The CRT display is generally known for its ability to produce good color compatible with color CRT. The disadvantages of CRT are as follows: low luminance for outdoor applications; low contrast at high ambient illumination operating condition; short lifetime at high luminance operating condition; expensive display device due to complex structure and high anode voltage of about 10 kv.
D. Hot Cathode Fluorescent Display:
Hot cathode fluorescent technology has been used in a display system called “Skypix” (SID '91 Digest. p. 577, 1991) which is able to generate a high luminance of about 5000 cd/m
2
and can be operated at direct sunlight. The disadvantages of this system are: low luminous efficiency due to hot cathode and short gas discharge arc length; very high power consumption and short lifetime because of the hot cathode and too many switching times for video display.
At present, the incandescent lamps are commonly used for an outdoor character and graphic display.
The matrix flat CRT, including food beam CRT and matrix CRT, is the most common display for an outdoor video display. Neither of these two technologies presents a display system which can be used in both indoor and outdoor applications possessing unique features overcoming all or substantially all of the disadvantages described above.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide a very high luminance large screen and ultra-large screen display using a shaped cold cathode fluorescent lamp (“CCFL”) with a special reflector and luminance enhancement face plate etc. It can be used for both indoor and outdoor applications even at direct sunlight. The dot luminance of the character and graphic display can be up to 15,000 cd/m
2
or more. The area average luminance of the full-color image can be up to 5000 cd/m
2
or more.
It is another object of the present invention to provide long lifetime large screen and ultra-large screen displays. The lifetime can be up to 20,000 hours or more at high luminance operating conditions.
It is one more object of the present invention to provide high luminous efficiency, low power consumption large screen and ultra-large screen displays. The luminance efficiency can be up to 30 lm/W or more.
It is a further object of the invention to provide a high contrast large screen and ultra-large screen display with the appropriate shades, black base plate and luminance and contrast enhancement face plate.
It is still a further object of the present invention to provide good temperature characteristics in large screen and ultra-large screen displays with a temperature control means. The CFD of the present invention can be used for both indoor and outdoor applications, and any ambient temperature condition.
In accordance with the present invention, a CFD is provided including some shaped R, G, B CCFLs, and R, G, B filters, reflectors, a base plate, a luminance and contrast enhancement face plate, a temperature control means, and its driving electronics to control the lighting period or lamp current or ON/OFF of CCFLs according to the image signal, and to control the luminance of CCFLs to display the character, graphic and image with monochrome, multi-color or full color.
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GL Displays, Inc.
Majestic, Parsons, Siebert & Hsue P.C.
Patel Ashok
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