Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Reexamination Certificate
2002-04-01
2004-05-11
Clinger, James (Department: 2821)
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
C313S440000, C335S213000, C348S828000
Reexamination Certificate
active
06734613
ABSTRACT:
FIELD OF THE INVENTION
This application is related to the field of cathode ray tube (CRT) technology and more specifically to thin profile cathode ray tubes (CRTs) and thin electron beam controllers and their use in image display on televisions and computer monitors.
BACKGROUND OF THE INVENTION
Cathode Ray Tube technology has long dominated the television (TV) market and is also found in the computer market as computer monitors. Television picture tubes and computer CRT monitors use well known principles of electron beam deflection and scanning over phosphor covered CRT front screens to produce high quality visual images. Initially, using a single electron gun to generate an electron beam, television images were generated in only a black and white. Later, with the advent of the tri-color electron guns, and appropriate control logic, color images were produced. This has remained the standard for over 30 years.
Even with the advent of larger screen flat panel Liquid Crystal Displays (LCDs) and, recently, plasma displays, CRT technology continues to dominate the consumer television and computer market. While flat panel displays have certain advantages over CRTs, they also exhibit significant disadvantages. A comparison of the characteristics of flat panel displays compared to CRTs is discussed in “Flat-Panel Displays and CRTs” published by Van Nostrand Reinhold Company, New York, 1985. This comparison shows that CRTs continue to exhibit superior picture quality, durability and affordability over other display technologies.
Consumer demand has continually pushed television and CRT technology. First better quality images were demanded, then color images, and currently very large screen television with significant quality improvement, e.g. High Definition TV. However, CRT based televisions are generally limited to a typical size of 36 inches diagonally. Above this size, CRT technology experiences a number of significant problems. One problem is that as the diagonal dimension of the front screen of a CRT or picture tube increases, the weight of the tube increases, as the glass must be made thicker to maintain the necessary vacuum level within the picture tube. Another problem is that as the picture tube size increases, the size and weight of the electron beam controller, or yoke, used to direct the electron beam across the face of the picture tube increases. This increase in size is necessary to achieve a greater deflection of the electron beam to reach the outer edges of the larger picture tube face without undue image or color distortion. Still another problem is the current maximum deflection angle is limited to about one hundred twenty degrees (120°) as there is a need to maintain focus and color convergence of the three-color electron beams at the outer edges of the picture tube. Furthermore, as the size of the conventional cone-shaped magnetic yoke increases, both the mechanical structure and the magnetic field generated reach points of diminished return with regard to power consumption and beam defocusing. Hence, to achieve images greater than those displayed on a conventional 36-inch diagonal television, manufactures have developed front projection and back projection televisions. These systems optically enlarge an image produced by a much smaller CRT television and direct the enlarged image to a front panel. However, projection television does not have the image quality of a CRT of a comparable size.
Hence, there is a need in the industry for large screen CRTs and electron beam controllers that achieve much higher beam deflection and also do not exhibit significant increases in size or weight as the size of the CRT diagonal dimension increases.
SUMMARY OF THE INVENTION
A thin cathode ray tube display system and associated components are disclosed. The system comprises a thin cathode ray tube a body having a substantially flat back element and a front element attached wherein a vacuum is maintained in the body, a neck element attached substantially perpendicular to the flat back element, wherein the neck element contains at least one electron gun for the emission of electrons, a transparent screen attached to the front element, the transparent screen having at least one phosphor layer operable to emit a photon of known wavelength and a substantially flat electron beam controller attached substantially perpendicular to the neck element operable to deflect an electron beam emitted by the at least one electron gun. The flat electron beam controller comprises a plurality of coil sets oppositely positioned with regard to the neck to deflect the electron beam horizontally and vertically, wherein each of the coil sets further comprises at least one coil arranged on at least one ferrite disk in a substantially trapezoidal shape.
REFERENCES:
patent: 4197487 (1980-04-01), Takenaka et al.
patent: 4490703 (1984-12-01), Ruth
patent: 4833432 (1989-05-01), Ohtsu et al.
patent: 5550522 (1996-08-01), Dekkers et al.
Clinger James
Duane Morris LLP
Tran Thuy Vinh
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