DEVICE FOR LIMITING THE MAGNETIC EMISSION IN CATHODE RAY TUBE MONITORS

Abstract: The device is foreseen with two or more turns of copper conductor wire (7, 8, 9 and 10), fitted near the deflection yoke (1, 2, 3 and 4), through which the current responsible for the same deflection is running, and their shape is foreseen so as to form a magnetic field configuration as like as possible and contrary to the unwished one. A drastic reduction of the magnetic field issued outwards the device will thus occur.

Description: Device for limiting the magnetic emission in cathode ray tube monitors. The invention refers to a proceeding which can be employed with de vices using cathodic ray tubes, which enables to theorically annul the emission of low frequency magnetic rays, without thus injuring the health of the persons. The invention device carries out an ad¬ aptation of an already existing one; consequently, the above form of elaboration is in connection with the shape of the device to which it must be suited and acts on it as a limiting device for the issue of low frequency magnetic radiations. Any device using cathodic ray tubes, such as monitors, T.V. recei¬ vers, etc..., at present gives out low frequency magnetic radiations. The investigations carried out in this connection have ascertained that such radiations are noxious to the human body, and particular¬ ly to pregnant women. It is well known, moreover, that the farmful- ness of the magnetic fields is mostly due to the deflection yoke, which beside giving rise to inside magnetic field essential for the deflection itself, dispels an unwished magnetic radiation outside the monitor. The invention device allows the solution of this problem through a proper means suited to the present devices in order to create a ir gnetic field exactly opposite to the disturbing one, thus annull- ing the noxious radiation. Substantially, the device is foreseen with 3O or more windings of copper conducting wire itted near the deflexion yoke through which the current causing the deflection is passing and its shape is such to create a magnetic field configu ration as like as possible and opposite to the unwished one. A dra- stic reduction thus results of the magnetic field issued outwards from the device. An elementarized scheme of the invention applied to a conventional deflection yoke is schematically illustrated in fig. 1 of table 1. The deflexion yoke is schematically consisting of the coils 1 , 2, 3 and 4 through which the relevant currents are passing after hav¬ ing been generated by the circuits of the monitor or T.V. receiver. For carrying out the suiting elaborations, according to the inven- tion, the four compensating coils 7, 8, 9 and 10 are foreseen in se_ ries connection with the relevant coils 1, 2, 3 and 4, and coiled in such sense and shape to annul the magnetic field outside the cathodic ray pipe 11. For operation, taking for instance the main coils 4 and 2 of the de¬ flexion yoke and supposing that the current running through it giv-- es rise to a magnetic field of the polarity indicated in fig. 1, the compensation coils 8 and 10 in the same instant will produce a magne tic field with the polarity shown in the same figure, which will com pensate the magnetic fields produced by the coils 4 and 2, thus annul], ing, or at least reducing, the magnetic field outside the system it ¬ self. The invention foresees the change of the compensation reel number; moreover the connexion type of the compensation coils may change in respect to the main coils, thus determining, for instance, sche mes in series, in parallel or others. Moreover, the position in the space of the compensation bobbins may change. The said spools can also be coiled on a support in either iron-magnetic material or not.

Claims: Claims. 1) Device for limiting the magnetic emission in monitors with catho die pipes, characterized by the fact that four compensating bobbins (7, 8, 9 and 10) in copper conducting wire are foreseen in series connection with the relevant main bobbins (1, 2, 3 and 4) coiled in such sense and shape to annul the magnetic field outside the catho¬ dic rays pipe (11) . 2) Device for limiting the magnetic emission in monitors with catho lic pipes, as per claim 1, characterized by the fact that if for o- peration two main bobbins (4 and 2) of the deflexion yoke are taken and supposing that the current running through them gives rise to a magnetic field with the polarity as per fig. 1 , the compensation bobbins (8 and 10) in the same instant will cause a magnetic field with the polarity shown in the same figure, which will compensate the magnetic fields produced by the main bobbins (4 and 2) thus annull¬ ing, or at least reducing, the magnetic field outside the same sy¬ stem.

Inventors: MEONI LUCIANO, MEONI, LUCIANO
Applicants: HANTAREX SPA
Application year: 1987
Main classification: H01J29
IPC codes: H01J29