U.S. Philips Corporation

Christianus H Bergmans

Fransiscus M Nooijen

Leonardus A Valkestijn

Erich J Palm

A diode modulator circuit which is adapted to supply an acceptable S-correction of the S-linearity error of the line scanning of a picture tube (CRT) at substantially different line scan widths. A known diode modulator has two loops. The first loop includes a series arrangement of a line deflection coil (LD) and an S-capacitor (CS), which series arrangement is arranged in parallel with a first flyback capacitor (CF1) and a first diode (D1). The second loop includes a modulator coil (LB) arranged in parallel with a second flyback capacitor (CF2) and a second diode (D2). The two loops are arranged in series. An inner-pincushion capacitor (CSM) is arranged in a common path in which the line deflection current (Id) and a modulator current (Ib) flowing through the modulator coil (LB) flow in opposite directions. The amount of S-correction depends on the values of the S-correction capacitor (SC) and the inner-pincushion capacitor (CSM). The S-capacitor (CS) has been omitted in the subject diode modulator. In this way, the amount of S-correction at minimal scan width will be zero because the common current (Im) flowing in the common path is zero if the diode modulator is in equilibrium. The diode modulator according to the invention can thus cope with picture tubes (CRT) which require a very low amount of S-correction at a small scan width without the need for an additional capacitor (CS2) and a thyristor switching circuit (T) to activate the additional capacitor (CS2) to lower the amount of S-correction at the small scan width.

Diode modulator generating a line S-correction

A power supply and scanning line deflection circuit for a picture display device. The power supply circuit comprises an inductance and a switch which switches at line frequency, the inductance forming part of a resonant network during the cut-off period of the switch. The line deflection circuit comprises another switch which also switches at line frequency and a line deflection coil which during the cut-off period of the switch, which substantially coincides with the retrace period, forms part of a resonant network which also comprises an inductance. A transformer winding is coupled to one of the inductances. During the cut-off period of the switch pulses are developed across this transformer winding which are rectified for generating a supply voltage for a variable load. To reduce the internal impedance of the voltage source thus formed, which may serve, for example as the high voltage supply, means are provided for connecting, at least during a portion of the scanning line retrace period, the transformer winding to the other inductance, such connection conducting substantially no current during the scanning line trace period.

Picture display device comprising a power supply circuit and a line

A power supply circuit for converting an input d.c. voltage into a first and a second d.c. output voltage. The power supply circuit includes the series arrangement of an inductor and a controllable switch for receiving the input voltage, the first output voltage being obtained from the resulting square-wave voltage across the inductor. A series resonant circuit followed by a peak-peak rectifier is coupled to the inductor for providing the second output voltage. Arranged as such, variations in a load connected to receive one of the output voltages has substantially no effect on the other output voltage.

Power supply circuit having two mutually independent outputs

A circuit arrangement for a picture display device for generating a sawtooth line deflection current. The arrangement comprises a power supply transformer having a primary winding and a secondary winding. One end of the primary winding is connected to a terminal of a supply voltage source and the other end to a controllable supply switch whose other side is connected to the other terminal of the source. The secondary winding is connected in series with a line deflection coil, a trace capacitor, and a deflection switch. A retrace capacitor is connected to the line deflection coil. During the retrace period the line deflection coil, the trace and the retrace capacitors are part of a resonant network the elements of which determine the duration of the retrace period. The secondary winding of the power supply transformer, the line deflection coil, the trace capacitor and the deflection switch are part of a loop to which a trace rectifier and an inductance, whose other end is connected to a voltage terminal, are connected, while a primary capacitor is coupled to the primary winding for partly determining the retrace period.

Circuit arrangement for a picture display device for generating a

A DC voltage to DC voltage converter where the period of a controllable switch is maintained for a period which produces current and voltage levels which will not damage any of the converter circuit elements. First and second voltage supply networks are provided, each comprising an inductor, one end of which is an input of the voltage supply network, the other end connected to first and second diodes. The second diode serially connects the inductor with a capacitor. The junction of the capacitor and second diode correspond to an output of the voltage supply network. The second voltage network receives the output of the first voltage network. The first diodes of each voltage network are connected to a transistor switch which is terminated by serially connected third and fourth diodes. A winding serially connected the junction of the third and fourth diodes with the second network output voltage junction. A tuning capacitor across the fourth diode establishes a resonant current in the winding. A signal from the winding is coupled to the transistor switch for changing the state of the transistor switch. Voltages across the transistor switch are established by the resonant tuning capacitor to a safe level. The converter is useful for providing horizontal deflection in a picture display device.

DC switching voltage converter for multiplying an input DC voltage

A circuit for a picture display device for converting an input d.c. voltage into a stabilized output d.c. voltage, comprising a transformer whose primary winding is part of a first resonant network and a switch switching at line frequency the conduction period of which depends on the output voltage. Through the primary winding there flows a first sawtooth current whose retrace period is determined by the elements of the first resonant network while the output voltage at the secondary side of the transformer is generated by means of a diode. A second resonant network is included between the diode and the switch and comprises an inductance, which can be a line deflection coil, through which a second sawtooth current flows. The retrace period thereof is determined by the elements of the second resonant network and both retrace periods are initiated at the same moment.

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Eindhoven, Netherlands

Christianus H Bergmans