Abstract: A cathode ray tube (3) (CRT) has a deflecting coil (1) surrounded by a funnel-like casing (4) of magnetic material. The deflecting coil generates a magnetic deflecting field (B) for the electron beam and a magnetic leakage field (BL) in the CRT environment. The leakage field is composed of a dipole field and a quadrupole field. To reduce the magnetic field strength in the CRT environment a magnetic compensation field which is counterdirected to the leakage field is generated. The compensation field is composed of a dipole field which is generated by a first compensation loop (7) and a quadrupole field which is generated by a second compensation loop (9). The first compensation loop (7) is substantially flat and at right angles to the magnetic deflecting field (B). The second compensation loop (9) is flat and at right angles to the longitudinal symmetrical axis (z) of the CRT and has an upper (9a) and a lower (9b) part which generate two mutually opposing dipole fields (DK2,DK3).

Abstract: A degaussing circuit for a video apparatus incorporates circuitry that controls various aspects of the degaussing operation. The control circuitry causes the degaussing current to be terminated after a period of time to eliminate the flow of residual degaussing current. The control circuit also causes the degaussing circuit to be reset, to enable redegaussing to occur. The control circuit also prevents redegaussing from occurring after a brief interruption of power to the video apparatus.

Abstract: A device for demagnetization of the picture tube of a television receiver and earthing of the conductive coating applied to the cone of the tube includes a demagnetization coil system (4) constituted by a bundle of insulated electric wires held together and forming at least one loop applied to the cone of the tube. The wires of the strand are held together by a tape of plastic material wound helically around them, while a bare electric wire (1) is wound helically with the same pitch as the tape. This wire is connected to earth (15, 16).

Abstract: A degaussing system for a CRT includes a voltage source, which is enabled by power-up of the CRT, coupled to a tank circuit including a degaussing coil and a capacitor. A voltage sensing network connected in parallel with the tank circuit senses the voltage across the capacitor and when that voltage rises to a predetermined threshold, and actuating signal is provided which turns on a latching switch circuit which enables a switch connecting the tank circuit to ground. This allows it to oscillate, taking the metal components of the CRT through a decreasing series of hysteresis loops as the oscillation decays. The latching switch circuit maintains the switch in an on position until power-down of the CRT, thus maintaining all except R1 which aids grid regulation of the components of the degaussing system, in a low voltage state until degaussing becomes necessary once again.

Abstract: A color cathode ray tube display includes a degauss coil and a switched mode power supply. The degauss coil is connected in series with the input rectifier (5) of the SMPS to limit the current surge on power on but is shorted out by a switch, preferably constituted by a triac, after the SMPS switching transistor turns on to give substantially zero residual degauss current. Forward voltage drop across the triac can be compensated for by back-to-back diodes (13) connected in series with the degauss coil. The triac is switched under control of a signal from an auxiliary winding on the SMPS output transformer (a).

Abstract: Certain applications require a CRT display to be well shielded against emitting RF electromagnetic energy. A shield placed at the neck portion of a CRT envelope inhibits RF emissions from being transmitted through the face portion of the CRT. The shield comprises longitudinal conductors for suppressing transverse magnetic (TM.sub.01, TM.sub.02 . . . ) mode emissions and circular conductors for suppressing transverse electric (TE.sub.01, TE.sub.02 . . . ) mode emissions. Placing the shield at the rear of the CRT envelope eliminates the need for covering the face portion of the CRT with an optically transparent screen. To eliminate RF emissions from the CRT display the housing is provided with a contiguous RF emission shield that is connected to the shield on the neck of the CRT. Alternatively, an internal RF emission shield would enclose the video circuitry which includes all potential sources of undesired RF emission.

Abstract: A degaussing apparatus for a video display includes a degaussing coil and a source of degaussing current. A switching means is coupled to the degaussing coil and to the source for providing a path for degaussing current between the source and coil during a degaussing operation. First and second PTC elements, functioning as degaussing current reducing means, are coupled to the degaussing coil and to the switching means. The switching means produces alternate coupling of the first and second PTC elements to the degaussing coil with respect to successive degaussing operations.

Abstract: A degaussing circuit for a video display apparatus eliminates residual degaussing current flow during operation of the video display apparatus. A capacitor is connected between coil of the degaussing relay and the source of energizing voltage. Application of the energizing voltage to the relay coil energizes the relay and initiates degaussing of the cathode ray tube of the video display apparatus, and also causes the capacitor to begin charging. As the capacitor becomes charged, the degaussing relay becomes deenergized, thereby terminating degaussing current flow. The capacitor charging time constant is selected to allow sufficient time for degaussing to occur before deenergization of the degaussing relay.

Abstract: First and second capacitors are charged prior to a degaussing interval. A first switch couples the first capacitor to a degaussing coil to initiate the degaussing interval. The first capacitor and the degaussing coil form a resonant circuit that resonates to generate a decaying degaussing current. During a predetermined portion of each cycle of the degaussing current, a second switch couples a precharged second capacitor in parallel with the first capacitor to form a charge transfer arrangement that transfers charge from the second to the first capacitor for replenishing energy losses in the first capacitor. The charge transfer arrangement increases the duration of the time it takes to the amplitude of the degaussing current to decay and, hence, the length of the degaussing interval.

Abstract: A vertical deflection amplifier of a video display apparatus includes first and second transistor amplifier output stages arranged in a totem-pole, push-pull configuration. A vertical deflection winding is coupled to the output stages at a deflection amplifier output terminal. An S-capacitor is coupled to the deflection winding at a second terminal remote from the output terminal. A source of deflection rate signals is coupled to the deflection amplifier for generating a deflection current in the deflection winding. A base current generating circuit is coupled to one of the transistor amplifier output stages for providing base current thereto. The S-capacitor voltage is applied to the base current generating circuit for enabling conduction of base current in the one amplifier output stage. When the video display apparatus is first turned on, the initially discharged S-capacitor is slowly charged from a DC voltage supply to delay generation of vertical deflection past completion of picture tube degaussing.

Abstract: A mounting and retaining assembly for a degaussing coil and ground strap for use on a cathode ray tube includes a flexible wire form that is held in place by the tube tension band. The wire is bent to form separate regions that receive the degaussing coil and ground strap. When the degaussing coil and ground strap are in place, the wire is under tension which holds the degaussing coil and ground strap firmly against the rear surface of the tube. The mounting and retaining assembly also includes retaining clips that cooperate and are held in place by the tube mounting lugs. The clips incorporate retaining loops that also receive and retain the degaussing coil and ground strap at other points.

Abstract: In a display device provided with a main substrate having the lower surface on which a metallic layer is formed and the upper surface on which at least a power source or a deflection circuit is arranged, a plate member having one surface formed by an insulating material and the other surface formed by a metallic material is placed with its insulating material facing the lower surface of the main substrate.

Abstract: A display device comprising a cabinet and an electromagnetic deflection yoke and a horizontal width adjusting coil received is the cabinet comprises a canceling coil for cancelling electromagnetic field noise generated from the electromagnetic deflection yoke received in the cabinet.

Abstract: A supply arrangement selectively operates from either one of dual AC mains supply voltages of, illustratively, 220 or 110 volt RMS AC. When the arrangement operates from the 220 volt AC mains supply voltage, a bridge rectifier, operating as a full-wave rectifier, charges each of series coupled first and second capacitors to one-half the peak of the AC mains supply voltage. During the positive half-period of the AC mains supply voltage, a positive voltage, equal to the difference between the instantaneous mains supply voltage and the DC voltage across the first capacitor is coupled between two terminals of a load such as a degaussing circuit. A corresponding negative difference voltage, is coupled between the two terminals during the other half-period.

Abstract: In a cathode ray tube apparatus having an in-line type electron gun, magnetic pole pieces comprising four pole pieces of substantially arc-shaped cross section are disposed in a cylindrical shape with circumferential gaps between neighboring pole pieces 0.degree., 90.degree., 180.degree., and 270.degree. locations on the cylinder. An additional pair of narrow width stripe-shaped pole pieces are disposed inside said cylinder at a predetermined distance from the cylinder in a manner to cover the 90.degree. and 180.degree. gaps. The apparatus acting to modify the horizontal and vertical deflection magnetic fields so that the electron beam spots on the phosphor CRT screen are substantially circular in shape without losing the self convergence effect of the magnetic fields.

Abstract: To correct the beam direction, and thus the color purity of color television tubes, particularly in tubes having fixedly secured deflection systems (10), the deflection field is, upon adjustment for color purity, additionally modified by introducing a unidirectional magnetic field extending with its field lines parallel to the z-axis of the tube. After adjustment to move a predetermined color, for example red, from non-deflected or hardly deflected central beam positions into the center of the CRT, the d-c unidirectional field is then disconnected, and the apertured mask demagnetized, as conventional. For demagnetization, the already present demagnetization coil (9) on the tube may be used, by applying a constant voltage thereto, for example of 12 V. The decaying demagnetizing field can be derived from a transformer connected to network power (FIG. 2) or through an oscillatory circuit formed by a charge capacitor (17).

Abstract: A color image display system includes a shadow mask type cathode-ray tube having a longitudinal axis, the tube including a panel, a funnel and a neck with a deflection yoke assembly encircling adjoining segments of the neck and funnel. A plurality of neck components are disposed around the neck of the tube. In one embodiment, an external magnetic shield is disposed along opposite sides of the funnel and neck of the tube. The shield extends across the longitudinal axis behind the neck for shunting magnetic fields from the tube while providing access to the deflection yoke assembly and the neck components. In a second embodiment, a second external magnetic shield is disposed orthogonal to the aforementioned external shield and spaced therefrom.

Abstract: A screening structure for a cathode ray tube display includes at least a cathode ray tube pin socket, a cathode ray tube input pin and a video amplifier section joined as one body and enveloped with a first screening member which has high conducting characteristics, and a cathode ray tube cathode section enveloped with a second screening member which has high conducting characteristics, the first and second screening members being connected as one body in order that they may be maintained at the same high frequency potential. The screening members are joined to the standard potential part of the cathode ray tube display by a cable having a low high-frequency impedance.

Abstract: A PTC thermistor device includes three PTC thermistors aligned and disposed in a heat transmission relation to each other such that the center PTC thermistor provides heat to the other PTC thermistors which are so connected as to define a part of path for the demagnetizing current. The two PTC thermistors positioned on the opposite sides of the center PTC thermistor increase their temperature rapidly so that a rapid and effective attenuation of demagnetizing current can be obtained.

Abstract: A cathode-ray tube has in a neck section of a hermetically sealed, evacuated envelope an electron-gun mount assembly in which of a cathode for emitting an electron beam, a first grid electrode section for forming a crossover point and for accelerating the electron beam and a second grid electrode section for focusing the electron beam are mounted on a plurality of insulative supporting bars. A conductive member is provided on an outer surface portion of the neck section, an inner surface portion thereof, and/or an outer surface portion of the supporting bars which surround a portion of the electron-gun mount assembly including the first grid electrode section but excepting the second grid electrode section.

Abstract: A degaussing circuit for a color television receiver has a continuously energized switch mode power supply feeding a voltage doubler coupled to a resonating capacitor connected in series with a degaussing coil for charging the capacitor while the receiver is off. A triac connects the capacitor and the degaussing coil in parallel when the television receiver low voltage on/off switch is turned on.

Abstract: A CRT in a CRT device is degaussed following a timed period of device inactivity and while the screen of the CRT is darkened, as well as at device turn-on or at manual activation. The screen stays darkened until data is inputted, and degaussing reoccurs during each subsequent timed period of inactivity.

Abstract: A degaussing system in a CRT device detects a trigger pulse and provides a timed control pulse which controls a power circuit "on" time. The power supplied to the degaussing coil is gradually reduced by the increasing resistance of a PTC thermistor in series with the degaussing coil, then turned off by the end of the control pulse. Degaussing can be initiated manually or automatically as often as desired, and may be triggered automatically in response to a predetermined period of device inactivity.

Abstract: A switched mode power supply for a remote controlled television receiver incorporates a degaussing circuit having a relay that is required to be energized in order to permit operation of the degaussing circuit. Power to energize the relay is derived from a power supply switch transistor protection circuit which removes residual stored energy from the power transformer primary winding. This stored energy is used to charge a capacitor during the time the switch transistor is nonconductive. The capacitor is discharged to provide current to energize the deguassing circuit relay in order to permit ac mains current to flow through the degaussing coil.

Abstract: The electromagnetic interference produced by arc discharge lamps and other devices operating at frequencies in excess of 15,000 Hz is reduced by providing a current path external to the envelope containing the discharge, the current flow in the path being oriented so as to produce a magnetic field generally in opposition to the magnetic field generated by the current in the arc discharge. The present invention is particularly applicable to circular fluorescent lamps with a centrally disposed ballast operating at relatively high frequencies.

Abstract: A radiation shield 14 for a cathode ray tube 10 neck 16 includes a sleeve 24 of insulating material. Bonded to the inner surface 26 of the sleeve 24 are a plurality of elongated, coaxially oriented spaced conductive elements 30. Similarly, a plurality of elongated, coaxially oriented spaced conductive elements 32 are bonded to the outer surface 28 of the sleeve 24. The inner elements 30 are offset from the outer elements 32. A conductive ring 40 is connected to each of the inner 30 and outer 32 elements along one end of the sleeve 24 and to ground potential by a drain strap 44.

Abstract: Light sensors with red filters are located at four corners of a CRT out of view of the operator. A red raster is generated in the corners of the CRT, the pattern of the raster corresponding to the area covered by the sensors. A pair of coils is located about the face of the CRT in a Helmholtz configuration and are driven by a current generator in response to the sensor output to maximize sensor output, thereby generating a compensating magnetic field which cancels external axial fields affecting the CRT.

Abstract: A demagnetizing coil is situated in an aperture frame removably mounted around the picture screen of a picture tube.

Abstract: A component consisting of two coupled PTC thermistors with the first thermistor having a lower cold resistance than the second thermistor and the first thermistor having a higher resistance at the operating temperature than the second thermistor. According to the invention, the electric connection to the second thermistor is made directly by solely mechanical contacts to the surface of the ceramic thermistor body. This means a considerable simplification during manufacture, as the second thermistor need not be provided with electrode layers.

Abstract: A single degaussing coil for a kinescope has a first portion located along a first side of the base of a generally pyramidal kinescope envelope or bulb. Second and third portions of the coil extend along portions of second and third sides of the base, and are joined by a fourth portion of the coil lying between the juncture of the neck and the bulb.

Abstract: An image pick-up tube assembly, including an image pick-up tube having a target provided in the front portion thereof, a coil assembly surrounding the image pick-up tube, a cylindrical shield case housing the image pick-up tube and the coil assembly, and front and rear shield caps covering the front and rear openings of the shield case. The front shield cap is mounted to the shield case such that both horizontal and vertical contact planes are formed therebetween to significantly reduce the influence of the earth's magnetism on the assembly so that a three tube type television camera employing three such assemblies is effected much less by direction dependent color deviation.

Abstract: In a remote controlled color television receiver, the television receiver power supply is responsive to the state of an on/off command signal. A DC supply voltage is applied to an input terminal of the power supply during both states of the on/off command signal, with the power supply developing an operating voltage at an output terminal only during the on-state of the command signal. A relay type switch is coupled to a degaussing winding and a source of alternating polarity voltage. The switch is responsive to the presence of the operating voltage and applies the alternating polarity voltage to the degaussing winding to generate degaussing current during the occurrence of, illustratively, the on-state of the command signal.

Abstract: The color picture tube is provided with a terrestrial magnetism correcting member contained in the tube and combined with a shadow mask assembly. The correcting member is shaped as a rectangular box made up of a pair of vertical magnetic side plates extending from the opposed sides of the supporting frame of the shadow mask and a second pair of horizontal magnetic plates interconnecting the upper and lower ends of the vertical side plates.

Abstract: A degaussing network of a remote controlled color television receiver is energized by a remote-responsive power supply rather than by the contact closure of a mechanical or electromechanical switch. The power supply includes a series-pass semiconductor element for developing a direct current voltage at an output terminal of the power supply derived from a source of alternating current voltage coupled across two input terminals. The regulator control circuit for the semiconductor element is responsive to the state of an on/off command signal. The power supply operates during the on-state of the command signal to provide the direct current voltage at the output terminal. The power supply regulator control circuit maintains the semiconductor element nonconductive in the off-state. The degaussing network, including a degaussing winding and a thermistor, is coupled to the output terminal of the power supply.

Abstract: A combined magnetic shielding and degaussing structure for an in-line color picture tube comprises magnetizable shielding plates of an extended surface area each located at a corner of the picture tube and two vertically oriented magnetizable strips. Each strip connects upper and lower corner shielding plates on one side of the picture tube. The shielding plates guide stray magnetic flux into the strips and away from the picture tube interior in order to provide magnetic shielding. A degaussing winding is wound around the vertical axis of each strip and generates a degaussing flux which flows through the shielding plates and into the color picture tube shadow mask.

Abstract: A multi-function system for use in a color television picture tube having a glass bulb includes a funnel and a faceplate with a rearward flange which mates with and is sealed to the funnel. A pre-formed coil of electrically conductive wire engirds the flange of the faceplate. The coil includes terminal means for connecting the coil to a source of degaussing current for abating residual stray magnetic fields within the tube. Annular enclosure means surrounds the flange and defines an enclosure containing the coil. A body of hardened binder is formed in the enclosure. The body is reinforced by the coil of wire and serves to provide implosion protection for the tube.

Abstract: An image-forming device, comprising an image intensifier tube, includes a magnetic shielding grid comprising a ferromagnetic material, which is arranged near the entrance screen of the image intensifier tube for the purpose of shielding against disturbing magnetic fields. Due to the use of partly radiation absorbing material and partly ferromagnetic material this shielding grid can replace, a stray radiation grid already present in the device, or can be added as a grid with radiation transmitting material and ferromagnetic material without the image formation being disturbed in any way.

Abstract: A degaussing circuit for a color television receiver, in which the degaussing coil is in series with a PTC thermistor to which an NTC thermistor is thermally coupled and which is at the same time a protection resistance for a supply voltage circuit in the receiver.

Abstract: A circuit arrangement for the demagnetization of color television receivers, in particular small battery fed receivers, comprising first switch means for charging a first capacitor immediately before demagnetization and second switch means adapted to be activated after the charging of said first capacitor for causing the capacitor to discharge through the demagnetization coil with short lasting current pulses of alternating direction. The arrangement comprises a second and smaller capacitor, which is charged and discharged by the current flowing through the demagnetization coil, this sequence being repeated in cyclic order.

Abstract: A magnetic shield device is provided wherein an object to be shielded from an ambient field is surrounded by a hollow member of high permeability material which has an opening therein permitting visual or other access to the object but also permitting possible entry of a disturbing portion of the ambient field. A counter magnetic field for opposing and cancelling the disturbing field portion is produced by current flow through a conductor wound around the path of the disturbing field portion, the conductor preferably being in the form of a solenoid coil wound around a tubular portion of the member. A DC current may be applied and/or the conductor may be short-circuited with the current being produced from a counter electromotive force induced from changes in the ambient field.

Abstract: A degaussing circuit, for example for a color television receiver, in which the degaussing coil is in series with a PTC-thermistor and in which the series arrangement thus formed is in parallel across a second PTC thermistor and across an a.c. voltage source, for example the supply mains. The thermistors are thermically coupled.

Abstract: A color television receiver includes a voltage regulating transformer and resonating capacitor for supplying power to receiver circuitry and to a color picture tube subject to extraneous magnetization. An automatic degaussing circuit includes a degaussing coil adjacent to the picture tube, a thermally responsive element and a tuning capacitor, all series connected across a portion of the transformer secondary winding.

Abstract: An improvement for effecting rapid warm-up of the thermionic cathode means in a color CRT display device utilizing a degaussing circuit including a temperature responsive resistive element in series with the primary winding of an inductive means. A direct operational relationship is established between the degaussing and cathode heater circuits by having the secondary winding of the inductor series coupled therein. Upon simultaneous activation of both circuits, through a common switching means, a transitory surge of current is supplied by the degaussing circuit to the heater circuit, via the common inductor, to effect an accelerated temperature response in the heater.

Abstract: A degaussing device for a color television display tube having three electron guns arranged in one horizontal plane and vertically directed phosphor strips on the display screen, comprising degaussing coils which envelop a major part of the conical surface of the tube and are arranged such as to generate a vertically directed magnetic field, and a capacitor connected parallel to the degaussing coils, the impedance of the capacitor being high at the frequency of the degaussing current and low at the frequency of the line deflection current.

Abstract: A color television receiver includes a voltage regulating transformer having an additional secondary winding coupled to the primary side of the transformer through a thermistor. A degaussing coil is supplied through another thermistor from the main secondary winding. Upon turn-on of the receiver, the additional secondary winding enables substantially higher current flow through the degaussing coil to assist in demagnetization of the permeable material in the picture tube.

Abstract: A degaussing winding adapted to be coupled to a first source of varying amplitude alternating current potential develops a degaussing flux in the proximity of a television picture tube during a degaussing interval. A secondary winding coupled to the degaussing winding supplies current to a power supply network to develop a first direct current potential during the degaussing interval. A further aspect includes means coupling the first direct current potential to a horizontal oscillator to enable start-up of the horizontal oscillator which provides for the development of a second direct current potential by the horizontal deflection system. The second direct current potential is coupled to the horizontal oscillator and sustains operation of the horizontal oscillator after the start-up interval.

Abstract: A color television receiver having degaussing coil means which are energizable by an alternating current source and which are disposed in demagnetizing relation to magnetically permeable materials in receiver components such as the receiver picture tube is shown to include resistor means of positive temperature coefficient of resistivity in series with the degaussing coil means. The resistor means are self-heating when energized and display progressively increasing resistance as resistor temperature increases, the resistor means further displaying a sharp or anomolous increase in resistance when resistor temperature increases to a selected level. Preferably, relay means responsive to this increase in temperature of the resistor are connected in parallel with the degaussing coil means to shunt the degaussing coil means as resistor temperature increases to said selected level.