Electric lamp and discharge devices – Cathode ray tube – Shadow mask – support or shield
Reexamination Certificate
2000-06-14
2003-02-25
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Shadow mask, support or shield
C313S269000, C313S461000, C313S402000
Reexamination Certificate
active
06525458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color selecting member in which a damper line for preventing vibration is provided in a tensioned state, a method of preventing vibration of the color selecting member, and a cathode ray tube having such a color selecting member.
2. Description of the Related Art
In a cathode ray tube, a color selecting member is provided for selecting an electron beam emitted from an electron gun, irradiating the selected electron beams only on phosphors of red, blue and green, respectively, and for projecting a video image according to each color onto a fluorescent screen.
FIG. 1
shows an example of the structure of a conventional color selecting member. The color selecting member
11
is what is called an aperture grille and is provided between a pair of frame members
13
under predetermined tension. A pair of arm members
12
are provided across both ends of the pair of frame members
13
.
The color selecting member
11
is constructed by a metal thin plate and has: a number of striped apertures
14
which are arranged at a predetermined pitch and through which an electron beam passes; and linear electrodes
15
each of which has a string structure and is provided between neighboring apertures
14
. The color selecting member
11
performs color selecting according to an incident angle of an electron beam entering the apertures
14
.
In such a color selecting member
11
, it is necessary to prevent occurrence of resonance due to vibration from the outside such as vibration caused by sound from a speaker, vibration caused during transportation between facilities at the time of manufacture of a fluorescent screen, and the like. Hitherto, the color selecting member
11
is therefore provided with two damper lines
16
constructed by thin metal lines which are in contact with the surface of the color selecting member
11
and are orthogonal to the linear electrodes
15
and apertures
14
. Both ends of each of the damper lines
16
are attached to damper springs
17
provided for the arm members
12
under predetermined tension.
In the cathode ray tube using the conventional color selecting member
11
, however, electron beams emitted from the electron gun are interrupted by the damper lines
16
which extend across the apertures
14
of the color selecting member
11
. It causes a problem such that the electron beams do not hit the phosphors on the fluorescent screen sufficiently, a shadow of each of the damper lines
16
is cast on a video screen and, as a result, the quality of the video image deteriorates.
It can be considered that the shadow of the damper line
16
on the video screen is made inconspicuous by reducing the diameter of the damper line
16
. In this case, however, since the strength at break of the damper line
16
deteriorates, the tension to press the surface of the color selecting member
11
has to be weakened. As a result, a problem lowering the effect of attenuating the vibration of the color selecting member
11
occurs.
Meanwhile, in recent years, in order to enlarge the screen while reducing the depth, a multiple electron gun type cathode ray tube having a plurality of electron guns has been developed. In such a multiple electron gun type cathode ray tube, as the screen becomes larger, the shadow of the damper line cast on the video screen becomes larger and more conspicuous.
SUMMARY OF THE INVENTION
The present invention was achieved in consideration of the problems with the aim of providing a color selecting member in which a shadow of a damper line cast on a video screen is made inconspicuous or the occurrence of a shadow is suppressed and yet whose vibration can be effectively prevented in a cathode ray tube having a plurality of electron guns, a method of preventing the vibration of the color selecting member, and a cathode ray tube having such a color selecting member.
A color selecting member according to the invention is used for a cathode ray tube having a plurality of electron guns and has a construction that a damper line for preventing vibration is provided in a tensioned state in a position opposite to an area on a fluorescent screen, which is irradiated with both electron beams emitted from neighboring electron guns. More specifically, when the color selecting member is used for a cathode ray tube in which electron beams emitted from neighboring electron guns cross each other before passing through a plurality of apertures, the damper line is provided in a tensioned state in an area through which both of the electron beams pass. When the color selecting member is used for a cathode ray tube in which electron beams emitted from neighboring electron guns cross each other after passing through the plurality of apertures, the damper line is provided in a tensioned state in an area through which both of the electron beams do not pass.
In a method of preventing vibration of a color selecting member according to the invention, a damper line is selectively provided in a tensioned state in a position opposite to an area on the fluorescent screen, the area being irradiated with both of the electron beams emitted from the neighboring electron guns, in accordance with whether the electron beams emitted from the neighboring electron guns cross each other before or after passing through the plurality of apertures.
Further, the cathode ray tube according to the invention has a color selecting member as described above.
In the color selecting member, the method of preventing vibration of the color selecting member, and the cathode ray tube according to the invention, since the damper line is provided in a tensioned state on an area of the color selecting member, which is opposite to the area on the fluorescent screen irradiated with both electron beams emitted from neighboring electron guns, a shadow of the damper line cast on the fluorescent screen can be lightened or prevented. That is, in the cathode ray tube in which the electron beams emitted from the neighboring electron guns cross each other before passing through the plurality of apertures, even when a shadow of the damper line is cast on the fluorescent screen by one of the electron beams, the other electron beam falls on the shadow, thereby lightening the shadow. In the cathode ray tube in which the electron beams emitted from the neighboring electron guns cross each other after passing through the plurality of apertures, neither of the electron beams hits the damper line, so that the shadow of the damper line is not cast.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
REFERENCES:
patent: 4780641 (1988-10-01), Hashiba et al.
patent: 4792720 (1988-12-01), Takenaka et al.
patent: 5365143 (1994-11-01), Nishimura et al.
patent: 5382871 (1995-01-01), Funahashi et al.
patent: 5525859 (1996-06-01), Ito et al.
“The Camel CRT: ISSN0098-0966X/2901/1998-SID” announced by A.A.S. Sluyterman (Philips Components).
Muraguchi Shoichi
Okada Masamichi
Guharay Karabi
Kananen, Esq. Ronald P.
Patel Nimeshkumar D.
Rader & Fishman & Grauer, PLLC
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