Abstract: In a switch-mode power supply, a transformer is used to transmit power during the forward-sweep time. The transformer is also used to transmit a control or regulating variable during the flyback time.

Abstract: In a vertical sawtooth generator of a vertical deflection circuit, a first comparator generates an output signal when a retrace portion of a sawtooth signal is at a first magnitude to initiate a vertical trace portion of the sawtooth signal. An amplifier responsive to the sawtooth signal and to a reference signal generates a feedback current at a time that occurs between the center of vertical trace and the end of trace and away from the center of trace. The feedback current is determined in accordance with a difference between the sawtooth signal and the reference signal. The feedback current is coupled to a first capacitor to develop a gain control voltage. The control voltage is applied via a voltage-to-current converter to an integrating capacitor to develop in the integrating capacitor the trace portion of the sawtooth signal. The control voltage is initialized during a power start-up interval.

Abstract: There is provided a circuit and method for generating a focus voltage having a predetermined waveform and magnitude for application to an electron beam focus means of a cathode ray tube having a display surface. A horizontal deflection current having a predetermined waveform and a frequency which is selectable over a predetermined range of frequencies is used to generate substantially horizontal scan lines on the display surface of the cathode ray tube by causing at least one electron beam to sweep across the display surface. The circuit has an input for receiving a signal having a current waveform representative of the waveform and frequency of the horizontal deflection current. In response to the received signal, the circuit produces a focus voltage output, the waveform and magnitude of which remain substantially constant over the range of selected frequencies of the horizontal deflection current.

Abstract: The most popular method for reducing stray emission effects in a cathode ray tube is to install a bleeder resistor at the flyback transformer of the tube. Such a bleeder resistor is, however, quite expensive. Therefore, the stray emission reduction circuit according to the invention differentiates the H pulse when the TV set is switched from "on" to "standby" which results in a higher duty cycle of the control transistor, implying a lower duty cycle of the horizontal output transistor HOT. This results in a lower voltage at the tuning capacitor and hence lowers the flyback peak voltage at the anode. This results in a drop of the EHT voltage.

Abstract: For the transmission of additional data on a television channel the lines of the vertical blanking interval are used. It is intented to improve program information by so-called electronic program guides, which are based on the transmission of a large database. For these EPGs the additional data shall be broadcasted within the teletext data stream in a compatible manner. The EPG data are splitted into two data streams, wherein the transmitted data are organized in data blocks. Data blocks from different streams may interrupt each other. According to the invention the data pages (A, B) are stored sequentially in two different buffers (PA, PB) and processed alternatively. The blocks of the pages transmitted in the first stream are stored in a first block buffer (BB1) and the blocks of the pages transmitted in the second stream are stored in a second block buffer (BB2).

Abstract: The invention relates to a switch mode power supply (SMPS) comprising control means (IP1) including an oscillator (OS) for generating a pulse-width modulated signal (V2). The object is to provide a fast start-up time over a wide mains input-voltage range (AC). According to the invention, the switch mode power supply comprises a network (T2, R52, R51, R24) which provides in case of a high input voltage a soft start with a low oscillating frequency and in case of low input voltage a start-up with essentially the normal oscillating frequency. The invention provides a fast start-up time over a wide mains input voltage range of 90 Volt up to 265 Volt. The network includes a transistor (T2) used in inverse mode as a switching element which provides a threshold value of about 150 Volt. The power supply can be used advantageously as part of a TV receiver.

Abstract: A deflection yoke for a cathode ray tube having a large, flat faceplate and a 4:3 aspect ratio includes a saddle-shaped vertical deflection coil. Most of the winding turns at a rear end portion are concentrated close to the beam entrance end of the coil. Both the position of the peak and the vertical deflection center of the vertical deflection field are shifted toward the gun entrance end with respect to the corresponding peak and deflection center of the horizontal deflection field. Consequently, North-South magnets are not required for reducing North-South pincushion distortion. Also, a much shortened yoke is obtained than if the peak were not shifted.

Abstract: A forward converter includes a chopper transformer having a primary winding and one or more secondary windings. A corresponding rectifier and a corresponding filter capacitor is coupled to each secondary winding. An inductor is coupled in series with the primary winding. A low impedance current path that includes the corresponding rectifier is formed between each secondary winding and the corresponding filter capacitor. The inductor limits the rate of change of the current in each current path.

Abstract: A bi-directional shift register for scanning a liquid crystal display includes cascaded stages. A given stage includes an output transistor having a clock signal coupled thereto. A first input section is responsive to an output pulse of a second stage for generating a control signal that is coupled to the transistor to condition the output transistor periodically for operation in a conduction state when shifting in a first direction is selected. The input section is responsive to an output pulse of a third stage for periodically conditioning the output transistor to operate in the conduction state, when shifting in the opposite direction is selected. When the clock signal occurs and the transistor is conditioned for the operation in the conduction state, an output pulse is generated at an output of the given stage.

Abstract: A display system includes a kinescope. A horizontal scan detector is coupled to a source of a horizontal scan current signal and detects a loss of horizontal scanning. In addition, a vertical scan detector is coupled to a source of a vertical scan current signal including a feedback path and detects a loss of vertical scanning. A vertical feedback detector is also coupled to the vertical scan current signal source, and detects a failure of the feedback path in the vertical scan current signal source. A controllable kinescope driver circuit, coupled to the kinescope, the horizontal scan detector, the vertical scan detector and the vertical feedback detector, blanks the kinescope if the horizontal scan detector detects a loss of horizontal scanning, the vertical scan detector detects a loss of vertical scanning or the vertical feedback detector detects a failure of the feedback path.

Abstract: In a tuned switch mode power supply a zero voltage is maintained across a transistor switch, during both turn off and turn on switching transition intervals in the transistor switch. The tuned switch mode power supply operates in a current-mode control, on a current pulse-by-current pulse control basis. A modulator of the power supply includes a pair of transistors that form a regenerative switch to produce a portion of a control signal of the transistor switch that causes the transistor switch to turn off. A transformer-coupled input supply voltage maintains the transistor switch conductive as long as the current in the transistor switch does not exceed the threshold level of a regenerative switch. A resonant pulse is transformer-coupled from the resonant circuit to the regenerative switch for turning off the regenerative switch and for maintaining the transistor switch non conductive after the regenerative switch is turned off.

Abstract: 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 as required for East-West pincushion raster correction. A pair of series coupled first and second capacitors forming a capacitive voltage divider are coupled to a retrace resonant circuit that includes the deflection winding via a sampling switch, during a first half of a retrace interval, to produce a first ramping capacitor voltage in the first capacitor from a portion of a retrace pulse voltage. The first capacitor is coupled to an East-West pincushion raster correction current source for producing a second ramping capacitor voltage in the first capacitor that ramps in an opposite direction. A comparator is responsive to the capacitor voltage for controlling a conduction interval of the East-West switching transistor.

Abstract: In a tuned switch mode power supply a zero voltage is maintained across a transistor switch, during both turn off and turn of switching transition intervals in the transistor switch. The tuned switch mode power supply operates in a current-mode control, on a current pulse-by-current pulse control basis. An over-current protection circuit disables the transistor switch when an over-current condition persist longer than a first interval that is substantially longer than a period of a given current pulse in the transistor switch. The operation of the transistor switch is undisturbed, when the over-current condition lasts only a shorter interval than the first interval.

Abstract: A controller for a switch mode power supply includes an undervoltage protection circuit responsive to an input supply voltage indicative signal. The input supply voltage indicative signal is also coupled to a foldback point correction circuit. The correction circuit causes a decrease in a maximum duty cycle of a control signal when the input supply voltage increases and is still smaller than a predetermined magnitude. A zener diode limits the input supply voltage indicative signal in a manner to prevent a further decrease in the duty cycle when the input supply voltage exceeds the predetermined magnitude.

Abstract: A liner of a deflection yoke is provided with non-threaded sleeves. A slide pin is inserted into the sleeve until a head portion of the pin comes in contact with a funnel of a cathode ray tube on which the yoke is mounted. After adjustment, a wedge is inserted into a hollow part of the pin for expanding radially the wall of the pin. Thereby, the pin is locked within the sleeve. In this way, the position of the yoke relative to the tube is secured.

Abstract: A deflection yoke for a cathode-ray tube, includes a pair of vertical deflection coils, a pair of horizontal deflection coils and a rigid separator insulating the pairs of deflection coils from each other. The separator has on its surface an arrangement for positioning and holding in place front and rear parts of saddle-shaped deflection coils. The arrangement forms an integral part of a body of the separator and is produced when molding the body.

Abstract: In a tuned switch mode power supply a zero voltage is maintained across a transistor switch, during both turn off and turn on switching transition intervals in the transistor switch. The tuned switch mode power supply operates in a current-mode control, on a current pulse-by-current pulse control basis. An over-current protection circuit disables the transistor switch when an over-current condition persists longer than a first interval that is substantially longer than a period of a given current pulse in the transistor switch. The operation of the transistor switch is undisturbed, when the over-current condition lasts only a shorter interval than the first interval.

Abstract: A vertical rate signal generator is coupled to an integrator for producing a vertical rate parabola signal. The parabola signal is applied to a band-pass filter for producing a vertical rate sinusoidal signal that is applied to a convergence winding. When a loss of the horizontal synchronizing signal occurs, the frequency of the sawtooth signal decreases. As a result, the DC, average level of the sinusoidal signal varies, during a transition interval, following restoration of the horizontal synchronizing signal. The band-pass filter filters out low frequency components. The duration of the transient interval is thereby reduced in a manner to reduce picture bounce. The peak amplitude of the sawtooth signal is also clipped for reducing the variation of the average level of the sinusoidal signal.

Abstract: In a switched capacitor type digital-to-analog (D/A) converter, a group of n bits of the binary word are applied to n parallel branches of the D/A converter, respectively. In a given branch, the corresponding bit is applied to a control terminal of a corresponding switch associated with a corresponding switched capacitor. Depending on the logic level of the bit, the switched capacitor is charged to a reference voltage or remains discharged. Then, the switched capacitor of the given branch is coupled by a transfer switch in parallel with a summing capacitor to provide for charge redistribution. The capacitances of the switched capacitor and of the summing capacitor are equal. The time allocated for either discharging the switched capacitor or charge redistribution is made shorter than the time allocated for charging the capacitor. Charging/discharging the capacitor is accomplished via a common transistor.

Abstract: An arrangement for reproducing a composite blanking or sync signal includes a vertical deflection circuit having a supply boost stage. A first pulse voltage at a vertical rate is derived from an output signal of the boost stage. The vertical rate, first pulse voltage is coupled to a base terminal of an emitter follower via a voltage divider for producing a leading edge of an output pulse voltage of the emitter follower. The vertical rate first pulse voltage is also coupled via an R-C network to a regenerative switch. The regenerative switch is coupled to the base terminal of the emitter follower for producing a trailing edge of the output pulse voltage of the emitter follower. The trailing edge is produced after a predetermined interval has elapsed from the leading edge. The output pulse voltage of the emitter follower is combined with a horizontal rate pulse voltage for producing the composite sync signal.