Excavating
Patent
1991-02-08
1994-05-24
Isen, Forester W.
Excavating
381 24, 381205, H04R 2500
Patent
active
053156633
DESCRIPTION:
BRIEF SUMMARY
In a television receiver it is known to incorporate within the receiver housing a loudspeaker enclosure for the sound reproduction disposed to the left and the right of the picture tube. Such a loudspeaker enclosure causes magnetic stray fields, and in particular, static stray fields caused by the loudspeaker magnets and dynamic stray fields caused by inductance from divider networks which divide the frequency bands between several loudspeakers. Such magnetic stray fields can cause interference in the picture tube and its circuitry in the form of color purity distortions or changing moving effects. This consists of interference, for example, visible forms which move across the screen in time with the sounds reproduced from the loudspeakers. Other metal parts of the loudspeaker enclosure, for example, hardware, metal loudspeaker frame, diaphragms made from aluminum and similar items, and the like can also influence the magnetic field within the picture tube and thereby lead to picture distortions upon reproduction. This influence on the picture reproduction caused by magnetic stray fields is particularly serious with new types of picture tubes with a screen diagonal size of 33 inches.
It is known to render disturbing magnetic fields ineffective by means of screening in the form of soft iron housings or mu-metal. However, this solution is relatively expensive and in particular with color televisions, cannot be introduced for reasons of cost and weight.
The influence of the magnetic stray field on the picture tube can also be reduced by increasing the distance between the loudspeaker enclosure and the picture tube. However, this solution is also not practicable because the enclosure is arranged within the housing and the size of the housing is restricted.
It is the object of the invention to minimize, on the one hand, the effect of stray fields on the picture tube magnetic fields caused by magnets and inductances, and on the other hand, the influence on the picture tube field caused by metal parts of the loudspeaker enclosure, hardware, frame and diaphragm.
SUMMARY OF THE INVENTION
A passive loudspeaker enclosure for a television receiver is present. Interference in the reproduced picture caused by magnetic stray fields from the enclosure occurs, in particular, with color television receivers with 33 inch picture tubes. The task is to reduce the magnetic stray fields by employing simple measures and without using additional components until the interference no longer appears in the picture. In particular, the exemplary embodiment of the present invention relates to a loudspeaker enclosure in a television receiver with a 33 inch picture tube.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-section of the loudspeaker, the housing and the rear housing component.
FIGS. 2A and 2B show views of the inside of the rear housing component.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is based on the following knowledge and considerations: For most of the components of an enclosure which contain metal and cause the afore-mentioned interference in the picture tube there exists a suitable alternative solution which is magnetically ineffective and does not cause impairment of the picture reproduction. If all these possible alternatives were made use of, and practically the only metal part left in the enclosure was the loudspeaker magnet provided with a magnetic field screening, then the magnetic interference fields in the picture tube can be brought under control such that the interference described no longer appears during picture reproduction. Therefore, through systematic use and combination of several individually recognized measures, the named task can be solved without significant additional expenditure and without impairing the function of the loudspeaker enclosure.
The housing for the enclosure, which preferably suits the shape of the picture tube, can be assembled from individual housing components without using metal parts, for example, with an adhesive connection or inte
REFERENCES:
patent: 3927261 (1975-12-01), Dahlquist
patent: 4410761 (1983-10-01), Schickedanz
patent: 4565905 (1986-01-01), Nation
patent: 4860370 (1989-08-01), Grosbard
patent: 5119429 (1992-06-01), Chatelain
Electronic-Werke Deutschland GmbH
Emanmuel Peter M.
Isen Forester W.
Le Huyen D.
Tripoli Joseph S.
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