US3801877A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for producing a region free from interfering magnetic fields
Assignee: Institut Dr Friedrich Foerster Pruefgeraetebau GmbH and Co KG
•
Filing: 1972-09-15
•
Granted: 1974-04-02
•
Expires: 1992-09-15
Abstract
Abstract Magnetic field generating coils are arranged at opposite sides of a region to be made free of interference magnetic fields along each of the three coordinate axes. A set of field sensing probes or transducers are also provided along the respective axes with compensation coils to prevent interaction with the field generating coils arranged along the other axes. As a further aspect, undesired interaction of the probes with control circuits of other equipment or devices being used in the region free from interference fields is suppressed by installing at each of the probe locations one or more compensating coils for nullifying the effect of these fields on the probes. Optionally, control amplifiers may be manually adjusted to compensate for fixed fields generated by other equipment being used in the region.
Inventors
- 👤 A Griese
- 👤 A Kalisch
- 👤 H Luz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:01
CPC Classifications
H; H01; H01F; H01F7/00; H01F7/06; H01F7/20; H01F7/202; H01F7/204
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
141 words
Apparatus for producing a space free from magnetic interference fields within which space systems sensitive to interference fields are located, such as electron microscopes, spectroscopes, and the like, comprising: probe means responsive to magnetic fields being located in the space to be free from interference fields for receiving the sum total of all the magnetic fields existing at the probe means location, said probe means generating electric signals generally proportional to the ambient magnetic field; means connected with said probe means for generating an electric current as a function of the sum total of all the magnetic fields received by the probe means; and coil means powered by the electric current for producing further electric fields in directions and of respective magnitudes such that the sum total of all the magnetic fields existing at the probe means location is substantially zero.
Claim 2
Dependent Claim
141 words
Apparatus for producing a space free from magnetic interference fields within which space systems sensitive to interference fields are located, such as electron microscopes, spectroscopes, and the like, comprising: probe means responsive to magnetic fields being located in the space to be free from interference fields for receiving the sum total of all the magnetic fields existing at the probe means location, said probe means generating electric signals generally proportional to the ambient magnetic field; means connected with said probe means for generating an electric current as a function of the sum total of all the magnetic fields received by the probe means; and coil means powered by the electric current for producing further electric fields in directions and of respective magnitudes such that the sum total of all the magnetic fields existing at the probe means location is substantially zero.
Claim 3
Dependent Claim
23 words
Apparatus as in claim 1, in which the probe means are located in the immediate vicinity of the systems sensitive to interference fields.
Claim 4
Dependent Claim
48 words
Apparatus as in claim 1, in which the probe means are arranged to sense magnetic fields preferentially along the directions of an orthogonal set of coordinates and the coil means are arranged so that magnetic fields generated thereby are directed along the field-sensitive directions of the probe means.
Claim 5
Dependent Claim
50 words
Apparatus as in claim 1, in which interaction of the coil means with the probe means is suppressed by the provision of compensating winding means on said probe means, and means providing a current to said compensating winding means of such polarity and magnitude as to cancel out the interaction.
Claim 6
Dependent Claim
60 words
Apparatus as in claim 1, in which interactions of fields produced by said systems sensitive to interference fields with the probe means are suppressed by compensating winding means wound on said probe means, and further means are provided for directing an electric current through said compensating winding means of such magnitude and polarity as to counteract the systems generated fields.
Claim 7
Dependent Claim
125 words
Apparatus for eliminating interference magnetic fields from a prescribed region in which field generating equipment is operated, comprising: first, second and third coil means arranged along the respective x, y and z orthogonal axes of said region; first, second and third magnetic field probe means located within said prescribed region and each respectively arranged to sense magnetic fields along one of the orthogonal axes of said region; individual processing circuits connected to said probe means for providing electric signals substantially proportional to the magnetic fields sensed by the associated probe means; and separate amplifying means interconnecting each processing circuit and the associated coil means for powering said coil means to produce a magnetic field in said region cancelling interference fields sensed by the probe means.
Claim 8
Dependent Claim
125 words
Apparatus for eliminating interference magnetic fields from a prescribed region in which field generating equipment is operated, comprising: first, second and third coil means arranged along the respective x, y and z orthogonal axes of said region; first, second and third magnetic field probe means located within said prescribed region and each respectively arranged to sense magnetic fields along one of the orthogonal axes of said region; individual processing circuits connected to said probe means for providing electric signals substantially proportional to the magnetic fields sensed by the associated probe means; and separate amplifying means interconnecting each processing circuit and the associated coil means for powering said coil means to produce a magnetic field in said region cancelling interference fields sensed by the probe means.
Claim 9
Dependent Claim
55 words
Apparatus as in claim 6, in which each probe means is provided with compensating winding means, and an individually selectively variable source of electric power is connected to each said compensating winding means for cancelling out in each probe means the effect of fields generated by the coil means located in the other coordinate axes.
Claim 10
Dependent Claim
50 words
Apparatus as in claim 6, in which each probe means is provided with compensating winding means, and an individually selectively variable source of electric power is connected to each said compensating winding means for cancelling out in each probe means the effects of fields produced by said field generating equipment.
Claim 11
Dependent Claim
61 words
Apparatus as in claim 6, in which there are provided first and second compensating windings on each probe means, and individual selectively adjustable electric power sources connected to each compensating winding the adjustment of which effectively cancels out for each probe means both the field effect of coil means in the other coordinate axes and that of the field generating equipment.
Claim 12
Dependent Claim
30 words
Apparatus as in claim 6, in which individual selectively variable electric power source means are connected to each amplifying means, individual adjustment of which compensates for relatively constant interference fields.
Claim 13
Dependent Claim
39 words
Apparatus as in claim 6, in which capacitor means interconnect each processing circuit with its associated amplifying means so that current changes in the coil means are only produced on changes in magnetic fields sensed by the probe means.
References Cited (Backward Citations)
US2697186A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |