Abstract: A deflection apparatus includes a pair of quadrupole arrangements for producing a pair of quadrupole fields in a beam path of an electron beam at different distances from a display screen. In an embodiment of the invention, the first and second quadrupole arrangements and a main deflection field producing arrangement cooperate to converge three electron beams, R, G and B, with one another.

Abstract: A deflection yoke for a video display system incorporates an arrangement for the introduction and distribution of adhesive to effect assembly of the yoke and mounting of the yoke to a cathode ray tube. A single adhesive inlet location transports adhesive through delivery channels to various locations about the deflection yoke to fix the relative positions of the horizontal and vertical deflection coils as well as mounting the yoke to a cathode ray tube.

Abstract: A video display apparatus includes a diode modulator for correcting side pincushion raster distortion. The diode modulator drive circuit produces a vertical deflection rate parabolic voltage that modulates the horizontal deflection current to effect pincushion correction. The drive circuit includes a transistor that has its base bias established by the combination of a width control resistor and a diode. The diode has the same thermal characteristics as the transistor to provide accurate temperature compensation. A resistor is connected between the emitter of the transistor and a supply voltage to change the transistor bias point in order to enable the transistor to be cutoff.

Abstract: A progressive scan video display apparatus incorporates beam landing error correction circuitry. Beam landing error correction may be accomplished prior or subsequent to video information interpolation and prior or subsequent to video information speedup. The correction circuits utilize sample interpolation techniques to provide accurate beam landing error correction for each of the red, green and blue video information signals.

Abstract: A regulating switched mode power supply for a video display apparatus provides electrical isolation between the load circuits and the AC line. A power transformer incorporates a regulator winding referenced to AC line ground potential. First and second feedback circuits develop first and second feedback signal components that are applied to a regulator control circuit which controls the conduction of the power supply switching transistor. The two feedback circuits have different time constants to accurately monitor load circuit loading conditions in order to maintain load circuit voltage level regulation.

Abstract: A video display apparatus incorporates a start-up and control circuit that is responsive to a bilevel signal indicative of the desired operating state of the video display apparatus. One state of the bilevel signal is effective to permit operation of the horizontal deflection circuitry and to generate a gating pulse for a voltage regulator circuit. The other state of the bilevel signal disables the horizontal deflection circuit which in turn disables the video display apparatus load circuits.

Abstract: A raster distortion corrector for a cathode ray tube includes magnetically permeable corrector pieces that are located on opposite sides of the deflection yoke. A part of each corrector piece is located within the external field of the vertical deflection coils and presents a low reluctance path to the external field flux. The flux is directed via a flux channelling arm of each corrector piece to a field shaper that causes a distortion correcting field to be formed between the corrector pieces. The flux channelling arms are formed and located so that there is no significant interaction of the corrector pieces with the horizontal deflection field.

Abstract: In a video display system in which a cathode ray tube exhibits blue bow misconvergence, a correction arrangement includes areas of magnetizable material located within recesses formed in the deflection yoke insulator. The material lies between the end turns of the horizontal coils along the sides of the yoke. The material is magnetized to form a four-pole field to effect correction of the blue bow error.

Abstract: A high voltage transformer incorporates a bobbin on which the primary winding is wound. The transformer auxiliary coils are wound directly over the primary winding with no intermediate layers of insulation. The wire turns of the auxiliary coils are evenly distributed over the full traverse of the primary winding to improve magnetic coupling and simplify tuning of the transformer.

Abstract: A video display apparatus operates at two or more horizontal scan rates. In order to prevent excessive collector voltage from being applied to the horizontal output transistor, a transition circuit turns off the horizontal output transistor when switching between horizontal scan frequencies occurs. The horizontal output transistor is maintained nonconductive until the correct oscillator frequency and supply voltage is coupled to the horizontal output circuit.

Abstract: A cathode ray tube protection circuit for a projection TV generates a signal which may be used to blank the tubes in response to a loss or reduction in beam deflection. Signals representative of vertical and horizontal deflection currents are provided. A reference signal is combined with the deflection representative signals to provide a signal having a predetermined amplitude. If the deflection current changes in any of the deflection yokes, the combined signal will change in amplitude. This change in amplitude is detected and used to generate a disabling or blanking signal for the kine driver circuits.

Abstract: A resonant degaussing circuit for a video display apparatus permits frequent degaussing during operation of the display apparatus. In order to provide effective degaussing for large screen cathode ray tubes, an inductor is connected in parallel with the degaussing coil. The inductor increases the degaussing resonant frequency so that a greater number of resonant cycles occur before the degaussing current decreases below a predetermined level.

Abstract: A drive circuit for a horizontal deflection circuit that is operable at a number of horizontal scan rates includes a pair of transistors coupled in a push-pull arrangement. The voltage supplies for the drive circuit transistors, which provide the forward and reverse drive for the horizontal output transistor, produce voltage levels that are dependent upon the horizontal scanning rate that is selected in order to minimize power dissipation during switching of the horizontal output transistor.

Abstract: A video display apparatus includes a regulated transformer power supply that provides power to an external load device, such as a computer, via one winding on the power supply transformer. Operation of the video display apparatus without the external circuit attached may cause degradation of the other transformer winding load circuits due to insufficient transformer power transfer as a result of decreased external power supply loading. A diode is connected from the external load supply to another load circuit to supply power to the other load circuit when the external device is not attached. When the external device is attached, the diode is reverse biased and does not conduct.

Abstract: Circuitry corrects vertical beam landing errors for color cathode ray tubes. A digital delay circuit provides horizontal scan line video pixel information at its proper location to produce a distortion corrected raster. Accurate correction is provided by a combination of scan line offset between the input and output video signals and by sample interpolation techniques that effectively form derived pixels that have an apparent location of the derived pixel relative to the sample video pixels is determined by the selection of the interpolating coefficients.

Abstract: A deflection yoke is mounted to a cathode ray tube by the use of two adhesives having different hardening rates. A first adhesive is applied between the yoke and the tube by a dispensing machine in a sufficient quantity to temporarily hold the yoke on the tube. A second adhesive having a hardening rate slower than the first adhesive is applied between the yoke and tube by the dispensing machine. The second adhesive purges the first adhesive from the dispensing machine. The quantities of the first and second adhesives are required to permanently mount the yoke to the tube. This arrangement may be used to assemble the yoke itself, as well as assembling the yoke and mounting it to a tube in the same operation.

Abstract: A video display apparatus having automatic frequency control circuitry for adjusting the frequency of a horizontal oscillator to provide oscillator synchronization with incoming horizontal synchronizing pulses incorporates an interface circuit for controlling the horizontal oscillator frequency response to frequency control output voltage. The interface circuit incorporates a two-transistor switch which provides a current path for charging the horizontal oscillator timing capacitor during a portion of the horizontal interval and a current path for bypassing the horizontal oscillator timing capacitor during another portion of the horizontal interval. The amplitude of the frequency control output voltage will determine the relative length of time that each of the transistors is conducting in order to provide a net increase or decrease rate in the charging of the oscillator capacitor, which in turn adjusts the oscillator operating frequency.

Abstract: A core gap spacing arrangement for a transformer includes a length of twisted wire pair. The twisted pair has a relatively low packing density and is therefore compressible over a large range by using relatively low compression forces, resulting in greater ability to accurately adjust the inductance of the transformer primary winding.

Abstract: A power supply provides a regulated DC voltage level for a wide range of AC supply levels. The power supply incorporates circuitry which forms a voltage doubler or a full wave rectifier in response to the level of the AC supply voltage. The transition between the type of rectification is rapid, so that the regulated voltage remains constant.

Abstract: A power supply and deflection circuit for a video monitor provides multiple horizontal scan rates. A switch is used to select the desired scan rate. Operation of the switch determines the proper operating voltage level for the horizontal deflection circuit. A zener diode provides a high or low signal in response to the level of the determined operating voltage. The horizontal oscillator frequency and the value of the S-shaping capacitor is determined in response to the high or low signal. The operation of the switch, therefore, provides the necessary circuit parameter changes for each of the horizontal scan rates selected.