DE1169990B - Phase comparison circuit for synchronizing the line deflection voltage in a television receiver - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN wffiWl · PATENT OFFICE

Boarding school KL: H04f;

EDITORIAL

Number:

File number: Registration date: Display day:

H04n

German class: 21 al - 35/12

T 21670 VIII a / 21 al
March 1, 1962
May 14, 1964

In a phase comparison circuit for synchronizing the line deflection voltage, a Comparison pulse obtained from the sync pulse with that derived from the local generator Comparing tactile pulse in phase and obtained a control voltage for the local generator. The pulse pulses are either from the local line generator or from the line transformer derived. Such known circuits can also be dimensioned so that they even if the line generator has fallen out of step, one that depends on the frequency deviation Generate control voltage that regulates the local generator back to the correct frequency.

It is known that the line return pulses used to obtain the sampling pulses are a Winding on the core of the flyback transformer. The one derived from this winding The voltage corresponds to the curve shape of the voltage of the low-voltage winding of the flyback transformer and, in addition to generating the probe pulses, it also serves to probe the tube for the probed shrinkage control, for generation a bias for the contrast control as well as for the dark control of the electron beam Picture tube during rewind. While the waveform is taken from this winding Voltage is suitable for the last three tasks, the withdrawn return pulse is for extraction the keying pulses are not suitable for phase synchronization because it is too wide for it. Must once namely the width of the return pulses at the peak value be smaller than the width of the flank of the Available comparison pulse obtained from the sync pulses. On the other hand, he must The peak value of the return pulse in the middle operating point of the phase comparison circuit approximates in time lie in the middle of the comparison pulse, which cannot be carried out with a wide pulse.

Since the return pulses do not meet these requirements by themselves, special circuit arrangements are required necessary to weaken and deform the line return pulses. Since the phase comparison circuit also contains two rectifier circuits controlled by the strobe pulses these circuits for pulse deformation may be provided twice.

Another disadvantage is that the shape and amplitude of the line retrace pulses from Beam current of the picture tube are dependent.

On the other hand, it is now known to have a winding on the flyback transformer (so-called high-voltage phase comparison circuit for synchronization
the line deflection voltage in one
Television receiver

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:

Alfred Pollak,

Ernst Karger, Hanover

voltage winding) with which the return pulses occurring during the line retrace are stepped up are to turn these increased voltage pulses by rectifying the high voltage to win for the picture tube. In order to achieve a further gain in voltage amplitude and To achieve a lower internal resistance of the high-voltage source, it is known, the high-voltage winding ζ. Β. by appropriately dimensioning their own capacitance to the third harmonic to match the line frequency (German Auslegeschrift 1038130). This harmonic is superimposed the fundamental wave corresponding to the curve shape of the low-voltage winding. This creates an increased impulse compared to the fundamental wave. The harmonic also arises in the Line retrace pulse obtained by winding close to the low voltage winding becomes, a dip, which makes this impulse useless for obtaining the tactile impulses. Around To avoid this disadvantage, it is known (German Auslegeschrift 1 026 355) on the core of the flyback transformer to provide an additional winding that generates a voltage with the waveform which decouples high voltage pulses. This tension becomes the one provided with the saddle Return pulse superimposed, so that the retardation of the return pulse, which is disadvantageous for phase comparison purposes is compensated. This solution requires an additional compensation winding. In addition, these return pulses are too high and too wide as tactile pulses.

The invention relates to a phase comparison circuit for synchronizing the line generator in

409 589/168

a television receiver, in the comparison pulses obtained from the sync pulses and from the Line return pulses obtained scanning pulses are compared in phase and thereby a manipulated variable to control the frequency of the line generator is obtained, the line return pulses can be taken from a winding on the flyback transformer and the flyback transformer a high-voltage winding ίο tuned to the third harmonic of the line frequency contains. The invention consists in the line retrace pulses can only be taken from a winding that is so firmly attached to the high voltage winding is coupled that a voltage with the waveform of the high-voltage pulses is induced in it.

For the recovery of the line retrace pulses for the phase comparison circuit is then only a single Winding required, which is only used to obtain the flyback pulses for the phase comparison circuit serves. In this way, enough narrow impulses are obtained, that is, for the Use as a key pulse no longer need to be deformed. Because the high voltage winding Pulses with very high voltage values lead and for the phase comparison circuit only pulse pulses significantly lower voltage are required, only agile turns are required for the winding. This winding can be designed so that the pulses taken from it just for the Control of the phase comparison stage have the desired amplitude and an additional weakening is also not necessary. Another advantage is that it is used as a key pulse The voltage peak on the high-voltage winding is approximately in the middle of the horizontal return, so that the above-mentioned requirement for the phase position between return pulse and comparison pulse is also fulfilled.

The invention is explained in more detail below using an example.

In Fig. 1, the core 1 of the flyback transformer carries a low-voltage winding 2 and a High-voltage winding 3. In the vicinity of the high-voltage winding 3, the winding is on the core 1 4 applied and grounded in the middle. At the two outputs of the Winding, probe pulses 5,6 are created, which have the necessary form for controlling the phase comparison stage and have amplitude. A few turns are sufficient for winding 4. With a tried and tested one In the exemplary embodiment, two turns were already sufficient to generate a key pulse amplitude of ± 22 V. The change in this amplitude with different loads of the The high-voltage source has no disadvantages for the function of the phase comparison circuit.

In Fig. 2 shows the different voltages on the flyback transformer. By overlaying the flyback oscillation 7, which corresponds to the voltage on the low-voltage winding 2, with the third Harmonic 8 of the line frequency results in the voltage pulse applied to the high-voltage winding 9 smaller width and larger height. The greater height is used to gain a higher high voltage. The smaller width of this pulse is used according to the invention to obtain the narrow tactile pulses 5, 6 exploited.

In Fig. 3 shows a circuit example of the invention. The sync pulse mixture containing the line and frame sync pulses are fed to the grating 10 of a separating tube 11. Through a Integrating member 12 in the anode line of the tube 11, the image sync pulses are separated and transferred a capacitor 13 is supplied to the frame synchronizer. The line sync pulses 14 are with a differentiating transformer 15 also located in the anode line of the separating tube 11 differentiated, so that at the output of the transformer 15 a comparison pulse 16 with a comparison edge arises, which is fed to the phase comparison circuit 18 via an AC combination 17. At the the other end is this phase comparison circuit of the winding 4 according to the invention with the Key pulses 5, 6 fed. By comparing the probe pulses with the edge of the comparison pulses 16 a control voltage is created, which is fed to a reactance stage 20 via a filter circuit 19, which influences the frequency of the line control generator 21.

Claims (3)

Patent claims: 1. Phase comparison circuit for synchronizing the line generator in a television receiver, in the comparison pulses obtained from the sync pulses and from the line return pulses obtained key pulses are compared in phase and thereby a manipulated variable to control the frequency of the line generator is obtained, the line return pulses from a winding on the flyback transformer and the flyback transformer one on the third harmonic contains high-voltage winding matched to the line frequency, characterized in that that the line return pulses are only taken from one winding (4) that is so firmly attached to the high-voltage winding (3) is coupled that induces a voltage with the waveform of the high-voltage pulses (9) in it will. 2. phase comparison circuit according to claim 1, characterized in that the winding (4) directly next to the high-voltage winding (3) on the same leg of the core (1) of the flyback transformer is arranged. 3. phase comparison circuit according to claim 1, characterized in that the winding (4) is dimensioned so that the line return pulses (5, 6) taken from it are used to control the Phase comparison circuit (18) required Am-. have plitude. Considered publications:
German interpretative document No. 1 026 355. 1 sheet of drawings 409 589/168 5.64 © Bundesdruckerei Berlin