Abstract: A predetermined rush current is set by a current setting switch (25). A digital-to-analog (D/A) converter (27) multiplies an attenuation curve signal input thereto from a read-only memory (ROM) (28) and the rush current thus set by the current setting switch (25) with each other and outputs a multiplied output to a D/A converter (29). The D/A converter (29) multiplies a signal input thereto from the D/A converter (27) and a sine wave signal read out from a ROM (30) and output a multiplied output to a field effect transistor (FET) (22) through an operational amplifier (24) to thereby control a degaussing current flowing through a degaussing coil (5). Therefore, a stable degaussing effect can be reproduced.

Abstract: A display device is described, comprising a display tube and a deflection unit. The high DC voltage (EHT) is generated by a line output transformer, this transformer receiving the flyback pulse during the line flyback period. This flyback pulse is transferred through the line output transformer and supplied as the high DC voltage (EHT) to the inner coating of the display tube. Variation of the high DC voltage causes radiation in front of the display tube. To overcome this radiation, a conductor is coupled between the ground terminal (or a metal shield coupled to the ground terminal) of the line output transformer and the outer coating of the display tube. This conductor has at least one turn around one of the coils of the deflection unit for generating a complementary variation to overcome the radiation in front of the display tube.

Abstract: A display corrector circuit 40 is disclosed which corrects for defocusing and horizontal and vertical spherical positional distortion of a point 22 upon a flat faced cathode ray tube display 16. The corrector 40 provides a plurality of programmable corrections and is based upon the first three terms of a Taylor series expansion of a polynomial functional representation of positional error.

Abstract: A method and apparatus for compensating the alternating electrical fields present at the front surface of a cathode ray picture tube wherein the high-voltage signal supplied to the high-voltage terminal of the tube is tapped to extract an alternating voltage signal therefrom, and the alternating voltage signal is inverted and amplified and then applied to a suitable external electrode placed in the proximity of the picture tube. The external electrode can be a framing band, an aquadag region or a ring electrode, among other things. Furthermore, combination of these electrodes can be employed.

Abstract: A demagnetizing circuit for a color picture tube includes a parallel combination of a relay coil and a negative temperature coefficient (NTC) resistor in series with the primary of the power supply transformer. The contact of the relay is connected into the degaussing circuit. As the NTC warms up the current through it increases and the current through the relay coil correspondingly decreases. When the current through the relay coil falls below the relay holding current the relay contact opens and the demagnetizing current ceases to flow.

Abstract: An electrostatic shield and method for shielding an electric field are presented, having particular application to the reduction of electric field emissions from a CRT display. The electrostatic shield is formed from a flexible non-conductive substrate and includes a plurality of radially disposed conductive elements. The shield is secured to the outer surface of the CRT, between the deflection yoke and screen, and the conductive elements are coupled to ground potential. In addition to a method for using the abovedescribed shield, a method is presented for shielding the electric field by applying conductive traces directly to the surface of the CRT, again between the deflection yoke and screen. These traces are coupled to the aquadag coating on the outer surface of the CRT, effectively grounding the traces and providing the desired shielding effect.

Abstract: A data display apparatus with a function for correcting the effect of external magnetic field including a display, a driving circuit for driving the display, an adjuster for adjusting a display position of input signal, a detector for detecting an output voltage of the driving circuit, and a difference detection circuit. The difference detection circuit detects a difference between an output of the detector when a predetermined reference signal is inputted as the input signal and an output of the detector when a display position of the predetermined reference signal is adjusted to a reference position on the screen of the display by the adjuster. The difference is stored in a memory as calibration data for correcting the effect of external magnetic field or the like.

Abstract: An improved degauss coil for use with cathode ray display tubes is disclosed. The degauss coil is formed from conductive traces placed directly on to a plastic part attached to or adjacent the front bezel surrounding the cathode ray tube. Alternatively, the conductive traces may be placed directly on to the bezel itself. The invention allows for a very narrow bezel border surrounding the cathode ray tube.

Abstract: A device for suppression of leakage of the magnetic flux in a cathode ray tube display apparatus which comprises at least a cathode ray tube having a face plate and horizontal beam deflection circuit generating the leakage, the deflection circuit comprising a pair of upper and lower coils each of which has a bend-up section producing a first magnetic field which deflects an electron beam of the cathode ray tube, and a second magnetic field produced as the leakage the first and second magnetic field forming a boundary plane therebetween, so that two boundary planes are formed of said upper and lower deflection coils, respectively, said device comprising; a pair of conductors each of which has a main portion and a lead portion connected to the main portion, said main portion of the pair of conductors being disposed approximately within said boundary plane and along approximately top and bottom rims of the face plate, respectively, said lead portion of the pair of conductors disposed along a side wall of a funne

Abstract: Unwanted electric fields in the area in front of a CRT can be produced by flyback voltage pulses which occur across the horizontal deflection coils and are coupled to the inner DAG coating of the CRT. The unwanted fields can be eliminated by providing voltage pulses equal and opposite to the causative voltage pulses and applying the provided voltage pulses to the inner coating and the anode button, leaving no fields to be cancelled in the relevant area.

Abstract: A degaussing current whose frequency is L Hz is supplied to a degaussing apparatus, and a constant amplitude vertical deflection current whose frequency is M Hz is supplied to a deflection yoke. The degaussing current is an A.C. current, and its frequency L Hz is determined such that the value of M/L is not an integer.

Abstract: In a cathode ray tube apparatus, a deflection yoke for generating an effective magnetic field to deflect electron beams in an envelope is provided around a funnel of the envelope. A pair of front magnetic coils are in substantially symmetrical with respect to a horizontal plane including a tube axis and a horizontal direction and are provided on a skirt of the envelope. A pair of rear magnetic coils are also arranged in substantially symmetrical with respect to the horizontal plane and are provided on the deflection yoke. Leakage magnetic fluxes generated from the deflection yoke are reduced by compensating magnetic fluxes generated from the front and rear magnetic coils.

Abstract: A shielded CRT (18) display includes a secondary shielding enclosure (14) for enclosing the CRT (18) and for inhibiting electromagnetic emissions therefrom. A primary shielded enclosure (12) internal to the secondary shielding enclosure (14) has a portion coaxial (16) with the neck portion (22) of the CRT (18) for also inhibiting electromagnetic emissions from the CRT (18). The CRT (18) includes an internal conductive layer comprised of an internal aquadag, wire mask, and phosphor coating. This internal conductive layer is grounded via a reactive path to ground to suppress electromagnetic emissions. This double shielding suppression technique eliminates the need for external shielding of the face portion of the CRT (18).

Abstract: The circuit includes a probe (6) for detecting a horizontal magnetic field and a first and a second circuit means (15, 17) driven by said probe (6) so as to create respective axial and lateral components of compensation of the horizontal magnetic field, that are in the same direction and of equal intensity, but of opposite sign to that of the magnetic field under test.

Abstract: A compensating coil for a scanning electron beam display such as a color television tube reduces undesirable deflection of the electron beams due to ambient magnetic fields, in particular the geomagnetic field. A first coil section has at least one winding disposed to encircle the tube neck, perpendicular to the Z axis. Upper and lower coil sections are disposed above and below the first coil section, each inclined forwardly along the Z axis and having a loop encompassing an area extending in the X and Y directions generally following the surface of an internal magnetic shield. The coil sections are coupled in series. The upper and lower coil sections have a wider X axis dimension proceeding forwardly along the Z axis, being keystone shaped. Lateral lengths of the upper and lower coils sections connect to the first coil section at lateral sides, such that the compensating coil is a continuous winding. The first coil section may have two passes for each pass of the upper and lower coil sections.

Abstract: The invention provides a degaussing circuit using a relay having the circuit for the TV of a remote controller type including the standby-power taking-out device to drive a MICOM, the degaussing device using the applied ac power and the drive-power taking-out device to drive a TV, the device including; a control device to control said degaussing device, the drive-power taking-out device, and the standby-power taking-out device through the relay and to drive the TV, located among the output stage of the standby-power taking-out device, the input stage of the degaussing device, and the input stage of the drive-power taking out device. Obtaining the cleaner screen may be attained according to the present invention.

Abstract: A compensating coil for a scanning electron beam display, such as a color television tube, reduces undesirable deflection of the electron beams due to ambient magnetic fields, in particular the geomagnetic field. The coil has a winding disposed to encircle the tube neck, perpendicular to the Z axis. A degaussing coil is positioned on the tube envelope to provide for demagnetizing metal structures within the envelope. In order to provide more complete degaussing, the supply current to the compensating coil is interrupted during the degaussing operation. In order to prevent a charge from accumulating on the compensating coil, one terminal is coupled through a resistor to a source of reference potential.

Abstract: A deflecting yoke for a television receiver comprises a parallel circuit of leakage magnetic field erasing or cancel coils connected in series with a parallel circuit of horizontal deflecting coils. The leakage magnetic field generated by the horizontal deflecting coils is cancelled by applying a magnetic field in an opposite magnetizing direction. The inductances of the cancel coils can be separately adjusted by adjusting the tap position of an adjusting variable tapped coil connected in series with the cancel coils.

Abstract: An electric field cancellation system and method for reducing electric fields are presented, especially suited for use in reducing the magnitude of electric field emissions from a CRT display. Signals from the electric field sources of the display are used to generate counter signals of equal magnitude and opposite polarity to the source signals. These counter signals are coupled to a plurality of transmitters which effectively establish a counter electric field, or fields, of opposite polarity to the source fields. The net effect is substantial reduction in the electric field emissions from the display, and a resultant electric field of substantially reduced magnitude encountered by a display operator.

Abstract: A demagnetizer for generating a degauss magnetic field to a cathode-ray tube by supplying an output of an AC power source to a degauss coil via a thermistor of positive characteristic, wherein a voltage-dependent resistance element is connected in parallel with the degauss coil so as to prevent generation of any excessive degauss magnetic field.

Abstract: The device comprises a demagnetization coil (1) wound from electrically conducting insulated wire (5) and surrounded by an electrically insulating sheath (7). A connection member (17) is connected to the two ends of the wire (5). The connections (19) between the connection member (17) and the wire (5) are surrounded by an electrically insulating envelope constituted by a sheet (21) of electrically insulating foil, which is folded so that the connections (19) and the adjoining parts of the sheath (7) are disposed between the facing parts of the sheet (21). The edges of the sheet (21) conducting each other are connected to each other by means of a welding connection (23). The sheet is further connected by means of a welding connection (23) to the sheath (7) and to an envelope of the connection member (17). The sheet 21 constitutes an envelope for the connections (19), which is tight but for one lead-through opening for the connection member (17).

Abstract: A method for controlling the magnetic field value within a specific volume subject to an external ambient magnetic field wherein detection means detecting the value of the ambient magnetic field in the volume is included, together with compensation means for nulling the ambient field in the volume within a predetermined compensation range. The method and apparatus includes use of a deperming means for inserting a magnetizing field independent of the compensation means into the volume whenever the value of the ambient magnetic field detected becomes greater than the predetermined compensation range.

Abstract: The present invention provides an apparatus and methods to reduce the stray magnetic fields created by the yoke assembly of a cathode ray tube (CRT) visual display device, and emitted from the CRT enclosure. A pair of closed wire loops are brought into contact with the yoke at the point where maximum magnetic radiation is emitted. The magnetic flux emitted from the yoke is coupled into the wire loop pair, inducing therein a current which flows so as to produce an opposing magnetic field to that produced by the CRT yoke. A capacitor in series in the second loop serves to increase the magnitude of the magnetic field produced by the second loop. Measured at a distance, the counteracting magnetic field reduces the total magnetic field emitted from the CRT enclosure.

Abstract: A circuit for demagnetizing a mask in a color picture tube of a television receiver, in which a resistor with positive temperature coefficient is applied to the input alternating current when the receiver is turned on. A bridge rectifier is connected with one terminal, to a first pole of the alternating current source, via the demagnetizing coil that is mounted on the picture tube, and the resistor. The bridge rectifier has another terminal connected to a second pole of the alternating current source. A variable electronic switch interconnects the direct-current output terminals of the bridge rectifier. The variable electronic switch is controlled to continuously decrease current flowing through the demagnetizing coil to zero. For this purpose, a controlling voltage is obtained from a winding in a horizontal-frequency synchronized power-intake stage by flyback rectification.

Abstract: A method and apparatus for controlling the magnetic field value within a specified volume, subject to an external ambient magnetic field, wherein the method and apparatus employ a plurality of magnetic field sensors and an associated plurality of coils, together with an electrical drive circuit connecting each of the sensors to the associated coil and including a feedback coupling the output of each of said coils to all of said sensors.

Abstract: A magnetic field sensing and canceling circuit for use with a cathode ray tube (CRT) has a closed loop system consisting of flux gate sensors to measure external magnetic fields and magnetic field cancellation coils around the perimeter of the faceplate of the CRT to cancel the fields and thus minimize color and positional ac image distortion. The coils are mounted on an enclosure fabricated of a high permeability material and are positioned around the perimeter of the CRT's faceplate. Four of the coils are parallel to the top, bottom, and sides of the enclosure opening and a fifth coil is wound around the enclosure adjacent the CRT faceplate. The magnetic flux gate sensors provide output signals that are functions of the detected fields. These signals control the current in the magetic field cancellation coils and thus control the cancellation fields.

Abstract: At least two pairs of auxiliary coils are disposed externally on a deflection yoke at positions which are symmetric with respect to the central axis of a horizontal direction of said deflection yoke and which are separated from each other in the direction of the axis of a cathode ray tube. At least two pairs of auxiliary coils are respectively disposed in front of and at the back of the longitudinal center of a magnetic core. The auxiliary coils have a horizontal length which is longer than its another length. A horizontal deflecting current is supplied to the first pair of auxiliary coils in the direction in which unnecessary radiant magnetic fields generated in front of and at the back of the deflection yoke are suppressed, and a horizontal deflecting current is supplied to the second pair of auxiliary coils in the direction in which an unnecessary radiant magnetic field generated at the back of the deflection yoke is intensified.

Abstract: A method and apparatus for controlling the magnetic field value within a specified volume subject to an external ambient magnetic field wherein the apparatus includes a number of magnetic field generators each associated with one of a number of magnetic sensors. The disposition of the magnetic field generators with respect to one another and to the associated sensors is such that the total effect of current selectively applied to the generators is to produce within the volume a magnetic field in opposition to the ambient external magnetic field.

Abstract: A cathode ray tube has a funnel provided with an outer conductive coating that is electrically isolated from an AC mains supply. An insulated degaussing coil is fitted to the funnel against the outer conductive coating and energized by the AC mains supply in an electrically nonisolated manner. A spring includes a resilient body forming a spring action that snugly fits the degaussing coil against the outer conductive coating. The spring includes a clip for attaching the resilient body to the degaussing coil. At least one of the clip and the resilient body is made of an insulated material for preventing the resilient body from providing a conductive path with respect to electrical shock hazard between the degaussing coil and the electrically isolated outer conductive coating.

Abstract: Picture display device comprising a display tube, a deflection unit and a compensation coil system for generating a magnetic compensation field which is oppositely directed to the line frequency radiation field of the deflection unit in a space in front of the display screen. The compensation coil system comprises two coils each being wound on a rod-shaped core portion. The core portions are arranged in a V-formation in the y-z plane, symmetrically relative to the x-z plane. Alternatively, the compensation coil system may comprise two pairs of coils arranged in this way and located in planes parallel to the x-y plane and equidistantly therefrom.

Abstract: In order to compensate for the influence of magnetic fields on charged-particle beams, in particular in imaging devices provision is made for a coil constituted by a support plate of substantially constant thickness and by patterns deposited on the support in such a manner as to ensure that the absorption of electromagnetic energy is constant over the entire surface of the coil within a predetermined pass-band.In a first embodiment, the patterns are transparent to the electromagnetic energy of a desired frequency band. In a second embodiment, complementary patterns are employed in order to obtain constant absorption over the entire surface of the coil.

Abstract: An image rotation compensation circuit for use with a CRT. The compensation circuit includes a winding which encircles the CRT and is oriented transverse to the path of the electron beam. A controller is connected to the winding and drives a current through the winding to create a magnetic field. The direction and magnitude of the current may be adjusted by the user to substantially cancel an external magnetic field and thus eliminate any image rotation caused thereby.

Abstract: A magnetic cancelling apparatus for a color cathode-ray tube which is to cancel external magnetic fields acting on the color cathode-ray tube, can prevent deterioration of the screen color purity. The apparatus includes a magnetic sensor for detecting a magnetic field in a predetermined direction acting on the cathode-ray tube. The output of the magnetic sensor is amplified and then fed to a cancelling coil, thereby permitting the screen purity to be kept in best condition even under change in direction of the external magnetic field such as the geomagnetism.

Abstract: An arrangement for compensating against the magnetic field of the earth in a picture tube in remote-controlled video-display equipment, in which a compensating voltage is generated by a remote-control channel in the video-display equipment. This voltage is applied to a compensation coil in the picture tube. Current through the coil is adjusted in finely-divided incremental steps, and the current is continuously adjustable. The compensation voltage is applied to one end of the compensation coil, whereas the other end of the coil is supplied with substantially half of the operating voltage of the display equipment.

Abstract: A degaussing circuit for degaussing a cathode ray tube has a degaussing coil mounted on the back of the catode ray tube and a positive temperature coefficient thermistor connected in series with the degaussing coil. The resonance frequency determined by the degaussing coil and the positive temperature coefficient thermistor is set to be below about 14 kHz or above about 17 kHz.

Abstract: A system for improving the operation of a cathode ray tube (CRT) is disclosed whereby interference caused by external magnetic fields is mitigated. The system comprises a CRT having a CRT magnetic shield housing and at least one electromagnetic field sensor disposed adjacent to the inner surface of the CRT housing. Sensors form to generate a reference magnetic field and to generate a sensor output signal in response to the detection of both the reference field and an external field as sensed within the housing. A bucking field coil drive circuit is provided in electrical communication with the field sensor, the drive circuit being operative to generate a bucking field coil drive signal responsive to the field sensor output signal. A bucking field coil is disposed circumferentially about the CRT and is driven by the bucking field coil drive signal.

Abstract: Deflection unit mounted around a display tube for deflecting electron beams across the display screen includes a line deflection coil and a field deflection coil. A compensation coil system for generating a magnetic compensation field oppositely directed to the line frequency radiation field in a space in front of the display screen includes core means of a magnetizable material positioned between the display screen and the deflection unit in a plane parallel to the display screen and two diametrically arranged coils each having at least one turn.

Abstract: A method and apparatus for nulling the magnetic field within a specified volume in the presence of an external ambient field by generating compensating magnetic fields at a number of locations around the volume, sensing the field in the volume and controlling the value of the compensating fields in a closed loop system to null the field within the volume.

Abstract: In a television receiver, a magnetic field compensator of a horizontal component of the earth's magnetic field includes a fluxgate magnetometer having a pair of sensing windings for generating first and second sensing signals representative of corresponding components of the horizontal component of the earth's magnetic field. The sensing signals generate current in a pair of substantially planar coils disposed in a non-parallel vertical configuration on the rear periphery of a cathode ray tube. The currents in the coils produce a magnetic field that compensates or neutralizes the effect of the horizontal component of the earth's magnetic field on the electron beam in the cathode ray tube. Whenever the position of the receiver is changed, rotationally or geographically, the current in the coils is automatically adjusted to provide automatic neutralization.

Abstract: A picture display device having a display tube and a deflection unit comprising a field deflection coil and a line deflection coil is disclosed. To comply with a predetermined interference radiation standard, the picture display device is provided with one interference suppression coil or with a system of interference suppression coils, which interference supression coil or system of interference suppression coils is oriented and can be energized in such a manner that, measured at a predetermined distance from the picture display device, the strength of the local magnetic dipole field is below a desired standard.

Abstract: A magnetic shielding for a cathode ray tube. A magnetic shielding case surrounds the CRT funnel and side portions of the CRT front panel. Additionally a current coil is wrapped around the CRT. In one embodiment, the coil is wrapped completely inside the shielding case. In another embodiment, the coil is wrapped partially inside the shielding case and partially outside.

Abstract: To improve the trichromatic cathode tube shielding effect given by the frame-mask set and by a shielding material made with material of low magnetic permeability, the external conductors of a de-magnetization coil with two loops are made to pass in front of the fastening lugs and not behind the frit plane as was the case before, and the position of the internal conductors is set to obtain the best compromise.

Abstract: A method of, and a device for, reducing the magnetic stray field generated in the vicinity of the faceplate of a cathode ray tube by the deflection current in the deflection coils of the tube. A current loop (4) is arranged at a distance from the deflection coils and is supplied with current having a time function substantially coinciding with the time function of the deflection current. The stray field is thereby neutralized to a large extent in a region extending beyond the position of the current conductor (4) in a direction away from the faceplate.

Abstract: Picture display device having a display tube and a deflection unit comprising a field deflection coil and a line deflection coil. To comply with a predetermined interference radiation standard, the picture display device is provided with one interference suppression coil or system of interference suppression coils is orientated and can be energized in such a manner that, measured at a predetermined distance from the picture display device, the strength of the dipole component is below a desired standard.

Abstract: Cathode ray tube apparatus including compensation (14) for the vertical component of terrestrial and of other ambient magnetic fields (15). The compensation is achieved by the generation of an opposing vertical magnetic field by energization of the degauss coil (11, 12) in the apparatus. Two embodiments are described: one applies a continuous direct current (21) after the degaussing operation and the other applies a direct current component coincident with the degaussing signal to permanently magnetize components of the apparatus. The magnitude and polarity of the compensation provided may be variable.

Abstract: An image rotation compensation circuit for use with a CRT. The compensation circuit includes a winding which encircles the CRT and is oriented transverse to the path of the electron beam. A controller is connected to the winding and drives a current through the winding to create a magnetic field. The direction and magnitude of the current may be adjusted by the user to substantially cancel an external magnetic field and thus eliminate any image rotation caused thereby.

Abstract: As CRT display is housed in a magnetic shield to reduce the image distortions caused by the external magnetic field produced by an NMR scanner. To further improve image quality, three sets of compensating coils are positioned around the CRT display and inside the shield to produce magnetic fields which offset the effects of the residual external magnetic field components that penetrate the shield or enter through the window in the shield used to view the CRT screen.

Abstract: Picture display device having a display tube and a deflection unit (9) comprising a field deflection coil and a line deflection coil (11). In order to comply with a predetermined interference radiation standard, the picture display device is provided with a compensation coil system having a first set of compensation coils (18, 19) for generating a dipole compensation field and possibly a second set of compensation coils (18a, 19a) for generating a fourpole compensation field, the compensation coil system being preferably arranged in series with the line deflection coil 11 ) and being provided with electric means (R; R.sub.1 ; R.sub.2 ; R.sub.3 ; R.sub.4) to shift the phase of the current through at least a part of the compensation coil system with respect to the phase of the current through the line deflection coil.

Abstract: A deflection yoke apparatus comprises pairs of horizontal and vertical deflection coils. A coil separator is located between both coils. A deflection core forms a magnetic path for a magnetic flux generated from both deflection coils. An auxiliary coil is arranged at least a one position in a vertical deflection direction outside the deflection core. A horizontal deflection current is supplied to this auxiliary coil. A magnetic field, generated from the auxiliary coil, reduces an intensity of externally leaking magnetic field which radiates outside the deflection core when a horizontal deflection current is supplied to the horizontal deflection coils.

Abstract: A method for correcting magnetic field aberrations produced by eddy currents induced in a particle accelerator vacuum chamber housing is provided wherein correction windings are attached to selected positions on the housing and the windings are energized by transformer action from secondary coils, which coils are inductively coupled to the poles of electro-magnets that are powered to confine the charged particle beam within a desired orbit as the charged particles are accelerated through the vacuum chamber by a particle-driving rf field. The power inductively coupled to the secondary coils varies as a function of variations in the power supplied by the particle-accelerating rf field to a beam of particles accelerated through the vacuum chamber, so the current in the energized correction coils is effective to cancel eddy current flux fields that would otherwise be induced in the vacuum chamber by power variations in the particle beam.