Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Reexamination Certificate
1999-09-08
2001-04-10
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
C165S080300, C165S181000, C165S182000, C313S442000, C313S413000
Reexamination Certificate
active
06215239
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a cathode ray tube comprising means for generating at least one electron beam, a display screen and a deflection unit having coils for deflecting the electron beam(s) across the display screen, and a yoke ring which surrounds at least one of the coils, said yoke ring being provided with at least one cooling fin for dissipating heat generated by the coils, said cooling fin thermally contacting the yoke ring by means of lugs which contact a surface of the yoke ring. The invention also relates to a cooling fin for use in a cathode ray tube.
Cathode ray tubes are well known and are used, inter alia, in television receivers and computer monitors. A yoke ring having cooling fins for a cathode ray tube is known from JP-A 5-114370.
In operation, the deflection unit deflects the electron beam(s). The yoke ring surrounds the coils and enhances the field generated by the coils.
An important problem resides in that the temperature of the deflection unit increases during operation. The deflection unit warms up. This causes a number of problems. The different parts of the deflection unit expand and may move relatively to each other. These phenomena have a negative influence on the picture display. In the known yoke ring, the cooling fins are provided so as to dissipate heat.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide a cathode ray tube of the type mentioned in the opening paragraph, in which one or more of the above-mentioned problems are reduced in that the thermal contact between the cooling fin and the yoke ring is improved.
To achieve this, a cathode ray tube in accordance with the invention is characterized in that some of the lugs of the cooling fin are arranged so as to face the display screen with their respective free ends, and other of the lugs are arranged so as to face away from the display screen with their respective free ends.
As a result of this measure, the lugs of the cooling fins are operative on a larger effective contact surface of the yoke ring. This results in an improvement of the cooling effect of the cooling fin as well as an improved fixation of the cooling fin to the yoke ring. In addition, the possibility of adapting the cooling fin to the local shape of the yoke ring is further increased.
A favorable embodiment of a cathode ray tube in accordance with the invention is characterized in that the lugs are arranged in groups of three and, within a group, the central lug points with its free end in a direction which is opposite to the direction in which the outermost lugs point with their free ends.
This structure helps to obtain a desirably contacting cooling fin. This measure additionally results in the formation of a large effective contact surface, causing the deflection unit to be properly cooled.
Another favorable embodiment of a cathode ray tube in accordance with the invention is characterized in that, within a group of lugs, the central lug faces the display screen with its free end, and the two outer lugs face away from the display screen with their free ends. By virtue of this embodiment, it is precluded that, during providing the cooling fin around the yoke ring, in which process large forces are exerted on the cooling fin, the cooling fin is subject to deformation.
A further favorable embodiment is characterized in that the cooling fin is ring-shaped and provided with a circularly-symmetrical ridge, which is situated between the lugs and the outer circumference of the cooling fin. By virtue thereof, it is achieved that a good mechanical and thermal contact between the cooling fin and the yoke ring is maintained when said yoke ring is subject to thermal expansion.
An advantageous embodiment is characterized in that the cooling fin is provided with grooves or slits extending in a radial direction. As a result thereof, the resilient effect of the lugs is further improved, so that any deviations from a truly round shape of the yoke ring can be properly dealt with. This embodiment also increases the dimensional tolerances of the yoke ring.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.
REFERENCES:
patent: 2089340 (1937-08-01), Cobb
patent: 2140442 (1938-12-01), Clark
patent: 2402262 (1946-06-01), Sewell
patent: 2475604 (1949-07-01), Frisch et al.
patent: 2737370 (1956-03-01), Frisch et al.
patent: 2964688 (1960-12-01), McAdam
patent: 4737752 (1988-04-01), Kriz
patent: 5138290 (1992-08-01), Togane et al.
patent: 5598055 (1997-01-01), Inoue et al.
patent: 5668436 (1997-09-01), Honda et al.
patent: 5675213 (1997-10-01), Huang et al.
patent: 5114370 (1993-05-01), None
Japanese Abstracts: 6-243798(A), Sep. 2, 1994; 6-162962(A), Jun. 10, 1994; 4-123750(A), Apr. 23, 1992; 3-155028(A), Jul. 3, 1991; 3-152835(A), Jun. 28, 1991; 3-43941(A), Feb. 25, 1991; 1-200542(A), Aug. 11, 1989; 61-126744(A), Jun. 14, 1986; 61-126745(A), Jun. 14, 1986;.
Jansen Martinus H. E.
Kieboom Arnoldus M. C.
Day Michael H.
Santiago Mariceli
U.S. Philips Corporation
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