US3445730A

US3445730A - Television demagnetizer

Info

Publication number: US3445730A
Application number: US628718A
Authority: US
Inventors: Robert D Kahn
Original assignee: Fedtro Inc
Current assignee: Fedtro Inc
Priority date: 1967-04-05
Filing date: 1967-04-05
Publication date: 1969-05-20
Anticipated expiration: 1986-05-20
Also published as: DE6600015U

Description

May 20, 1969 R. o. KAHN TELEVISION DEMAGNETIZER Filed April 5, 1967 United States Patent US. Cl. 317157.5 8 Claims ABSTRACT OF THE DISCLOSURE A television demagnetizer which permits one-hand operation and ensures automatic current cut-off. A ring-like structure is provided with a projecting handle. A wire is coiled inside the ring and its two ends are brought out through the handle. A spring switch in the handle controls completion of the electrical circuit.

This invention relates to television demagnetizers, and more particularly to a construction therefor which permits one-hand operation, ensures effective demagnetization and provides for automatic current cut-off.

It has been found that as a result of many external factors, such as the earths magnetic field, electrical storms and the use of household appliances, there is a tendency for residual magnetic fields to develop on the screen of a television set and the surrounding metal parts. The residual fields deleteriously affect proper operation of the set, particularly in the case of color television. Various arrangements have been devised for demagnetizing the affected regions. Typically, a wire coil, through which an alternating current flows, is swept across the television screen to erase the magnetized regions.

Various problems have been encountered however in the use of prior art demagnetizers. Typically, the wire coil is contained in a ring-like enclosure, with the two ends of the wire coming out of the ring and being connectable to a wall socket. To sweep the ring across the television screen it has usually been necessary to grip the ring with both hands. This has been found to throw the user off balance, or in the alternative to effect a poor demagnetization unless many sweeps across the screen are made.

Another problem with prior art designs is their overheating. If a switch is not provided to control the flow of current a user might forget that the plug is inserted in a wall socket. If he does not remove it after the set is demagnetized the unit may disastrously overheat. Although an on-oif switch may be provided this is also unsatisfactory. A user may forget to turn off the switch just as he may forget to pull out the plug.

It is a general object of this invention to provide a television demagnetizer which overcomes the aforesaid disadvantages of the prior art demagnetizers.

Briefly, in accordance with the principles of my invention, I provide a ring-like structure with a projecting handle. The wire is wound in the ring and its two ends are brought out through the handle to the line cord. One of the wire ends passes through a spring-type switch projecting through the handle. Unless the switch is pushed in current cannot flow through the coil even if the plug is inserted in a wall socket.

This arrangement overcomes all of the aforesaid problems. First, only one hand is required to effect the television demagnetization. The handle can be gripped with one hand as the ring structure is swept across the television screen. Second, the switch is on the handle and can be operated by a finger on the gripping hand. When the demagnetization is completed and the unit is put down, the switch automatically cuts off the flow of current when it springs back to the open position.

3,445,730 Patented May 20, 1969 ice It is a feature of my invention to provide for a television demagnetizer a ring-like structure with a projecting handle, the handle being grippable by a single hand and having a normally open switch thereon to cut off flow of current through the demagnetizing coil.

Further objects, features and advantages of my invention will become apparent upon consideration of the following detailed description in conjunction with the drawing, in which:

FIG. 1 is a front view, shown partially cut away, illustrating a first embodiment of the invention;

FIG. 2 is a sectional view taken through line 22 of FIG. 1;

FIG. 3 depicts the electrical circuit used in the various embodiments of the invention;

FIG. 4 is a front view of a second illustrative embodiment of the invention;

FIG. 5 is a sectional view taken through line 5-5-of FIG. 4;

FIG. 6 is a front view of a third illustrative embodiment of the invention;

FIG. 7 is a sectional view taken through line 7-7 of FIG. 6; and

FIG. 8 is a front view of a fourth illustrative embodiment of the invention.

FIG. 3 depicts the basic electrical circuit used in all of the illustrated embodiments of the invention. A wire 23, typically made of aluminum and coated with polystyrene, is wound in a coil. Although only a few turns are shown, it is to be understood that in practice a number of turns, in the order of one-thousand, would be used. One end, 19, of wire 23 is connected through line cord 13 to plug 25, and the other end, 22, is connected to metal contact 24. Adjacent metal contact 24 is another metal contact 15. Contact 15 is connected by wire 14 through line cord 13 to plug 25. Even if the plug is inserted in a wall socket no current flows through the demagnetizer coil because in the

normal position contacts

15 and 24 are separated. Contact 15 is in the form of a metal spring which is mounted in the handle of the unit such that it is biased away from contact 24.

When push-button 16 is pressed inwardly, however, the two contacts are engaged and current flows through the coil. The alternating current throught the coil produces an alternating magnetic field perpendicular to the plane of the drawing. As the coil is swept across the screen of the television set the alternating magnetic field demagnetizes the residual magnetization.

Referring to FIGS. 1 and 2, demagnetizer unit 20 is constructed of two

plastic sections

30, 11 which fit together as shown. Section 11 is fiat and forms a face for section 30. Section 30 is provided with a screw bore 24. Screw 21 is inserted through a hole in face 11 into the screw bore and when tightened locks the two sections in place. Additionally, an adhesive may be used to fasten the two sections together.

The two sections define an annular cavity in which wire 23 is coiled. End 19 of wire 23 is connected to the conductor within insulating jacket 18, extended up through handle 12. End 22 of wire 23, on the other hand, is connected to the tip of metal contact 24. This contact is anchored in the handle by lugs 31 as shown in FIG. 2. (The lugs are omitted in FIG. 1 for the sake of clarity.) Similar lugs 32 (FIG. 1) are provided for anchoring metal contact 15 in the handle. The lower end of metal contact 15 is connected to wire 14 within insulating jacket 17. (In FIG. 2 wire 14 is shown broken off since metal contact 15 is to the rear of metal contact 24 and the drawing would erroneously show wire 14 connected to the latter metal contact.) Spring metal contact 15 is anchored in the handle by lugs 32 in a manner such that it .is biased away from contact 24.

Push-button 16 extends outward through a hole in handle 12. Spring contact 15 biases the button outward. But when handle 12 is gripped and button 16 pushed in, it forces contact 15 to engage contact 24 and current flows through the coil. This construction not only enables the demagnetizer to be swept across the television screen with the use of only one hand, it also enables a finger on the same hand to control switch 16. Furthermore, after the unit is used and placed aside, the electrical circuit is broken even though plug 25 may remain inserted in the wall socket.

In the embodiment of FIGS. 4 and 5, section 42 of demagnetizer 40 includes an internal annular ring 45 for engaging seats 46 in section 49. Handle 43 on section 49 is inclined with respect to the plane of the ring as shown in FIG. 5. Handle 43 is integral with section 49 except that during its formation it may be constructed of two parts in order that the various electrical connections be made within it. The connections are similar to those shown in FIGS. 1 and 2. The embodiment of FIGS. 4 and also includes an additional name plate 47 attached by two screws 48 to the handle. It should be noted that in the second embodiment of the invention push-button 40 faces toward the front of the unit rather than to a side.

In the embodiment of FIGS. 6 and 7, the ring-like structure 60 includes a front section 61 and a rear section 67. A fiat flange 62 is disposed across the upper portion of the interior of the ring, the flange having a rim 69 along a chord of the ring. Handle 63 is bent as shown in FIG. 7 and attached to the rim of the flange. Push-button 64 extends outward toward the front of the unit. Rim 69 includes a bore 68 along its length through which the two ends of the wire coil are directed to the handle, one from each side of the rim. Bore 68 is shown in FIG. 7.

In the embodiment of FIG. 8, demagnetizer 80 is in almost all respects similar to the demagnetizer of FIGS. 1 and 2 except that handle 82 projects outward from ring 81 rather than inward. Again, the push-button 83 is on the side of the handle rather than on its front.

During the degaussing (demagnetization) operation the energized unit is swept across the screen parallel to it. The entire operation typically requires only ten or fifteen seconds. Upon completion it is preferable to keep the unit energized and parallel to the screen as it is withdrawn away from the set. When the unit is a few feet away from the set the switch should be released.

Although the invention has been described with reference to particular embodiments it is to be understood that these are merely illustrative of the application of the principles of the invention. Numerous modifications may be made therein and other arrangements may be devised without departing from the spirit and scope of the invention.

What is claimed is:

1. A television demagnetizer comprising a ring-like enclosure having a cavity therein, said enclosure having a face adapted to be placed against the screen of a television set and swept thereacross, a hollow handle connected to said ring-like enclosure and extending therefrom such that the enclosure and handle are symmetrical in configuration about the longitudinal axis of said handle, said handle being connected to said enclosure such that the interior of said handle and said enclosure cavity form a continuous cavity, an insulated wire coiled around within said enclosure cavity and having two ends brought into the hollow of said handle, a line cord having two conductors each extending through said handle to the hollow therein, means for connecting a first of said conductors to one of said wire ends, a normally open electrical switch having two ends, means for connecting a first end of said switch to the other of said wire ends, means for connecting the second of said switch ends to the second of said conductors, and a finger engageable button extending from said handle hollow through a hole in said handle to the exterior thereof and adaptable to close said electrical switch.

2. A television demagnetizer in accordance with claim 1 wherein said handle projects inwardly from said enclosure along a diameter thereof.

3. A television demagnetizer in accordance with claim 1 wherein said handle projects outwardly from said enclosure along a diameter thereof.

4. A television demagnetizer in accordance with claim 1 further including an internal flange coupled to said ring-like enclosure and extending inwardly thereof, said flange having thereon a rim extending along a chord of said ring-like enclosure, said handle being connected to said rim and disposed in a plane other than the plane of said enclosure, and a bore extending through said rim for coupling said enclosure cavity to said handle hollow.

5. A television demagnetizer in accordance with claim 1 wherein said handle extends inwardly of said ring-like enclosure along a diameter thereof and is inclined with respect to the plane of said ring-like enclosure.

6. A television demagnetizer in accordance with claim 1 wherein said first switch end is a metal contact anchored in said handle and said second switch end is a tip of a metal spring, and further including means for anchoring said metal spring in said handle such that the other tip thereof is adjacent said metal contact but disengaged therefrom, said extending button being operative to move said other tip of said metal spring to engage said metal contact.

7. A television demagnetizer in accordance with claim 2 wherein said first switch end is a metal contact anchored in said handle and said second switch end is a tip of a metal spring, and further including means for anchoring said metal spring in said handle such that the other tip thereof is adjacent said metal contact but disengaged therefrom, said extending button being operative to move said other tip of said metal spring to engage said metal contact.

8. A television demagnetizer in accordance with claim 7 wherein said button extends outward of said handle in the plane of said ring-like enclosure.

References Cited UNITED STATES PATENTS 3,281,742 10/1966 Kaplan et al. 317-1575 XR 3,329,871 7/1967 Smith 317-157.5

JOHN F. COUCH, Primary Examiner.

W. M. SHOOP, JR., Assistant Examiner.

US. Cl. X.R. 3l58; 335-284