Abstract: A deflection yoke mounted on a neck of a cathode ray tube includes a pair of horizontal deflection coils, a pair of vertical deflection coils and a core of a ferromagnetic material. The core has magnetic reluctance, in a front region, close to a screen end of the tube, that is greater along the vertical direction than along the horizontal direction. In one embodiment of the invention this feature is achieved by making recesses at the intersection of a flared front part of the core with the horizontal plane of symmetry XZ. In another embodiment of the invention, the thickness of the core varies.

Abstract: In a video display, correction data for a digital convergence arrangement are stored in a first non-volatile memory. During power turn on procedure, the correction data are read out of and stored in a volatile memory. During each deflection cycle, the data stored in the volatile memory are successively read out and applied to an auxiliary convergence winding. When a parity error is detected in the read out data, an output and/or an input of a convergence amplifier is actively disabled to prevent a disturbance of a screen of the cathode ray tube.

Abstract: The invention relates to a process and device for scanning cells of a matrix-controlled display for the displaying of grey levels of a video signal, the scan being split up into sub-scans relating to each bit of column control words, characterized in that, when the coding of image does not activate the high-order bit, the processing sub-scan relating to this bit is allocated to the displaying of an additional item which corresponds to a bit of lower weight than the smallest weight of the column control word used when the condition is not fulfilled. The applications of the invention relate to matrix-controlled display devices using the principle of temporal modulation for the generation of halftones, especially plasma panels of the a.c. type with memory or d.c. type with memory.

Abstract: The present invention relates to a method for addressing a flat screen composed of lines and columns, with pixels located at their intersections, characterized in that, at the start of each sampling of the video signal to be displayed on the screen, a voltage (Vr) higher than the working voltage range (V) is applied to the selected pixel for a time tr, then the working voltage is sampled for a time ts.

Abstract: A video display deflection apparatus includes a vertical deflection coil. A separator is used for mounting the vertical deflection coil thereon. The separator has a funnel shaped first part conforming to a shape of a neck of the cathode ray tube and a second part forming a front portion of the separator close to the screen. A degree of flare of the first and second parts is substantially different. A saddle shaped, horizontal deflection coil is mounted on the separator for producing a deflection field to scan the electron beam along a horizontal axis of the display screen. The horizontal deflection coil includes a plurality of winding turns forming a pair of side portions, a rear end turn portion, close to an electron gun of the tube and a front end turn portion, close to the screen. At least a portion of the front end turn portion, in a radial angular position ranging between 0 and 30 degrees, is supported on the second part of said separator away from the boundary.

Abstract: A series arrangement of an isolating diode and an East-West switching transistor is coupled between a flyback transformer primary winding and a horizontal deflection output transistor circuit to control retrace energy to obtain an East-West modulation of the deflection current amplitude. A first inductor, a tapped inductor and an S-shaping capacitor are coupled via a switch to form a resonant circuit, during the first half of trace. The tapped inductor includes a portion forming a current path for a deflection current. The tapped inductor develops a voltage that controls the switch. The first inductor, the tapped inductor and the S-shaping capacitor are coupled via the switch to form the trace resonant circuit, during the first half of trace. The trace resonant circuit provides inside pincushion raster distortion correction.

Abstract: A resistive voltage divider is responsive to a parabolic voltage developed in an S-shaping capacitor of a deflection circuit operating at a selected deflection frequency. The voltage divider includes a controllable resistive network for automatically selecting an attenuation factor of the voltage divider in accordance with the selected deflection frequency. An amplifier responsive to the attenuated parabolic voltage generates at an output terminal of the amplifier a periodic output voltage that is capacitively coupled to a focus electrode to produce a dynamic focus voltage. In a first embodiment, the controllable resistive network includes a photoresistor that provides automatic gain control. In an alternative, second embodiment, the voltage divider is switched.

Abstract: A video display deflection circuit includes a source of a periodic, first signal that varies in accordance with a position of an electron beam on a screen of a cathode ray tube. A limiter is responsive to the first signal for generating a second signal having a limited, piece-wise linearized first portion, when the first signal is outside a range of values. The second signal has a second portion that varies, when the first signal varies within the range of values. A modulator is responsive to the second signal and to a video signal for generating a modulated correction signal coupled to an auxiliary deflection winding to produce, in accordance therewith, scan velocity modulated deflection of the electron beam.

Abstract: A resistor-capacitor-diode clamp is coupled to an S-capacitance of a horizontal deflection circuit output stage for reducing ringing by causing critical damping. The supply voltage of the output stage varies at a vertical rate parabolic manner for modulating the horizontal deflection current to provide East-West correction. A clamp capacitor of the clamp has a terminal that is direct current coupled to the supply voltage. Therefore, each terminal of the clamp capacitor has the same vertical rate parabola component. Consequently, the DC voltage difference developed between the terminals of the clamp capacitor does not include any vertical rate parabola component, the result is that the sensitivity of the damping to the supply voltage vertical rate variations is, advantageously, eliminated or reduced.

Abstract: An electron beam tends to slope downwardly as it is deflected horizontally to form a raster in a video display apparatus. The sloping of the beam can cause geometric errors in the raster, for example orthogonality and parallelogram errors. A raster correction circuit substantially offsets the downward slope of the electron beam by modulating a vertical deflection current with an induced horizontal-rate raster correction current, thereby substantially eliminating orthogonality and parallelogram errors in the raster. A raster correction transformer utilizes a raster centering inductor for a primary winding, and a horizontal-rate centering current is magnetically coupled into the vertical deflection coils to modulate the vertical deflection current.

Abstract: A video imaging apparatus includes a source of a blanking signal that is indicative when a blanking interval occurs in a video signal. A delay circuit including a horizontal line counter is responsive to the blanking signal and to a signal at the horizontal rate for delaying the blanking signal by a multiple number of horizontal periods to generate a delayed signal. A dynamic focus voltage generator includes a switch responsive to the delayed signal for applying a dynamic focus voltage to a focus electrode, when the switch is at a first state, and for disabling the application of the dynamic focus voltage, when the switch is at a second state. An end time of the interval, during which the dynamic focus voltage is disabled, is determined in accordance with an output signal of the counter.

Abstract: A device for addressing a matrix screen such as a screen of the LCD or plasma type having a memory stage receiving, via a demultiplexing stage a plurality of sequences of digital data representing the previously digitized luminance video signals, and delivering the luminance video signals to a multiplexing stage designed to select a sequence of digital data corresponding to a given combination of subpixels from amongst the plurality of sequences of digital data previously stored in the memory stage.

Abstract: An ultor voltage switching power supply for a cathode ray tube is energized by a low voltage switching power supply. A switching transistor of the ultor voltage switching power supply is disabled when a screen of the cathode ray tube is blanked. An anode capacitance of the cathode ray tube that develops the ultor voltage discharges via a bleeder resistor, when the switching transistor is disabled. As a result, a transient decrease occurs in the ultor voltage. The decreased ultor voltage tends to maintain the screen blanked.

Abstract: A compensation process for a circuit comprising at least one first conductor at a specified potential, at least one second conductor generating disturbances by capacitive coupling to the conductor and at least one disturbance compensation bus capacitively coupled to the first conductor by a first capacitor includes the steps of measuring the voltage and the current on the compensation bus, calculating the voltage on the first disturbed conductor, and determining the set-point voltage to be applied to the compensation bus in order to compensate for the disturbance.

Abstract: In a horizontal deflection circuit output stage of a video display monitor capable of operating at multi-scan rates, a given S-capacitor, selected from a bank of S-capacitors, provide S-correction at a corresponding range of frequencies. A resistor-capacitor-diode clamp selected from a bank of clamps is coupled to the selected S-capacitor for reducing ringing by causing critical damping. The in-circuit selected resistor-capacitor-diode clamp is selectable, in accordance with the selected horizontal deflection frequency.

Abstract: When a main switching transistor of a zero voltage switching power supply is conductive, a voltage is developed in a current sensing resistor coupled in series with the transistor. The voltage in the current sensing resistor is coupled to a first input of a comparator of the control circuit. A second input of the comparator is coupled to a capacitor that develops a voltage that varies in accordance with an output voltage of the power supply. During a given conduction interval of the transistor, the comparator is triggered in accordance with the difference between the current sensing resistor voltage and the capacitor voltage. An output of the comparator is coupled to the base of the transistor for controlling the turn off instant of the transistor on a current pulse-by-current pulse basis. Under overload condition, when the transistor is turned off, a reverse collector current flows through the base-collector junction of the transistor.

Abstract: A cathode-ray tube includes an evacuated envelope having a faceplate panel with a sidewall joined to a funnel. Implosion protection band surrounds at least a portion of the sidewall and is in contact therewith. The band may include at a given location a pair of flair portions. A degaussing coil clip formed by a resilient or spring leaf material includes a pair of gripping tips that engage the band.

Abstract: A process for addressing cells of a plasma panel includes the step of coding the grey levels NG1 and NG2 relating to an item of information regarding the luminance of two cells situated in the same column and in two adjacent lines I and I+1. The grey levels NG1 and NG2 are coded as a first control word corresponding to a common value VC and as a second control word and a third control word corresponding to specific values, VS1 and VS2. The coding is such that, NG1=VS1+VC and NG2=VS2+VC. The process further includes the step of transmitting the bits of the first control word on the column inputs by simultaneously addressing the two lines I and I+1 in respect of the selection of the corresponding cells.

Abstract: A method for the control of a color alternating display panel having a written state and an extinguished state arranged in rows and columns, the rows forming at least two sets. A sustaining signal is applied to the rows. This sustaining signal generates discharges in the cells that are written in. The sets are addressed. An addressing operation consisting of a semi-selective operation followed by a selective operation. After a semi-selective operation pertaining to the first set, a preconditioning write operation is performed on the cells of one row of the second set, aimed at ionizing the panel. Application in particular to plasma panels.

Abstract: In a tuned switch mode power supply, a supply inductance is coupled to a capacitance to form a tuned, resonant circuit. A transistor switch is coupled to the resonant circuit for generating current pulses in the inductance, coupled to a load circuit to provide an output of the power supply. Resonant voltage pulses are developed between a pair of main current conducting terminals of the transistor switch. A controller is coupled to the transistor switch for generating a switch control signal, during a run mode of operation. The transistor switch is turned on periodically, when the resonant voltage pulses reaches a zero voltage, to provide for zero voltage switching. The generation of the current pulses is disabled to provide for a burst mode operation, in a standby mode operation.