DE1256250B - Circuit arrangement for generating time-proportional or stronger than time-proportional increasing control pulses for deflection stages of cathode ray tubes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

H04n

German KL: 21 al - 35/20

Number: 1 256 250

File number: St 23717 VIII a / 21 al

Filing date: April 22, 1965

Opened on: December 14, 1967

The invention relates to a circuit arrangement for generating time-proportional or stronger than time-proportional increasing control pulses for deflection levels in devices with cathode ray tubes.

It is known that for controlling vertical magnetic deflection devices in televisions the transformer coupling of the deflection stage is a parabolic component of the control pulse at the deflection output stage calls when the impedance of the primary inductance of the transformer in the Order of magnitude of the ohmic resistance of the vertical deflection coil comes. This achieves that the part of the current flowing through the deflection coil remains proportional to time.

On the other hand, for statically deflecting oscilloscope tubes, sawtooth voltages running as time-proportional as possible are required. If the required control voltages are generated with simple RC elements, only about 10% of the maximum possible voltage increase can be used due to the voltage increase according to an exponential function as an approximately time-linear part.

In order to achieve an additional parabolic component of the voltage rise, the negative feedback circuits possible in connection with a subsequent amplifier or output stage are used today. More complicated RC networks have also been proposed which can derive and add a parabola component from the voltage rise proportional to time. However, both methods lead to considerable control voltage losses.

When using the known circuits with the "tracking charging voltage", operating fluctuations have an effect due to the feedback effect as increased deflection amplitude fluctuations. Today one is general of this circuit got lost.

The invention is based on the object of avoiding the disadvantages mentioned.

The invention is characterized in that in the frequency-determining network of the deflection circuit a controllable capacitance is charged or discharged via an ohmic resistor, whereby the charging and discharging voltage controls the temporal instantaneous value of the capacity.

This circuit arrangement enables a significantly greater voltage yield with increased operational reliability. As a voltage-dependent capacitor, for. B. a capacitance diode, a selenium rectifier in the reverse direction or a ceramic circuit arrangement for generating
time-proportional or stronger than time-proportional increasing control pulses for distraction levels
of cathode ray tubes

Applicant:

Standard Elektrik Lorenz Aktiengesellschaft,

Stuttgart-Zuffenhausen, Hellmuth-Hirth-Str. 42

Named as inventor:

Dipl.-Ing. Wolfgang Schröder, Feldrennach

Capacitor, e.g. B. of the barium titanate type, use in conjunction with an ohmic resistor.

The structure and mode of operation of the arrangement according to the invention will be explained below with reference to the F i g. 1 to 4 explained.

F i g. 1 to 3 show basic circuit diagrams for different networks of the circuit arrangement according to the invention;

F i g. FIG. 4 shows an exemplary embodiment for a deflection circuit with the network according to FIG. 3.

In Fig. 1 is 1 the voltage-dependent capacitance, which reduces its capacitance with increasing voltage. After the switch 2 opens, which is implemented in particular by a periodically operating electronic arrangement such as a blocking oscillator or a multivibrator, the capacitance 1 is charged via the resistor 3 from the voltage source 4 according to the time constant R · C. Since C decreases with increasing charging voltage, the voltage increases progressively in a parabola-like manner over time.

The curvature of the rise over time can be shown in FIG. 2 with a fixed or variable additional preload (e.g. generated by means of a variable voltage divider 5/6 connected to the capacitor 7 for AC voltages is bridged) decrease or increase by placing the working area on the voltage-capacitance characteristic of the capacitor shifts.

Instead of this permanently feedable additional voltage, dynamically regulating counter or Feedback signals can be used by the subsequent amplifiers.

Another possibility for regulating the curve shape is shown in FIG. 3. The setting is made here via a change in the basic capacitance either with the possibly controllable capacitor 8 or by means of

709 708/273

of this series-connected adjustable resistor 9, which the capacitor 8 more or less coupled.

An exemplary embodiment of a tube-equipped vertical deflection stage for a television set is shown in FIG. 4th While the part of the circuit on the left is precisely the FIG. 2 corresponds, the in F i g. 2 shown simple switch 2 is replaced by an electronic switch, in this example a blocking oscillator. The automatic, periodic short circuit takes place here via the primary winding of the feedback transformer 11 and the anode-cathode path the triode 10. The period is in a known manner via the time constant of the frequency controller 13 and of the capacitor 12 is regulated, the feedback voltage becomes the secondary winding of the feedback transformer 11 taken.

The sawtooth voltage occurring at the anode of the tube 10 with the parabolic component adjustable at 6 is fed to the control grid of the pentode 16 via the coupling capacitor 14. The working point of this tube is via the grid leakage resistance 15 and the cathode resistor 17 are set. A capacitor 18 bridges the resistor 17 capacitive. 19 is the output transformer for deflection coil 20, which is the parabolic component of the current makes necessary.

If 19 and 20 are replaced by an ohmic resistor and the sawtooth-shaped voltage curve, which without the voltage-dependent capacitance tat 1 increases after an exponential function, by corresponding Setting 6 is linearized, you get a linear sawtooth at the anode of the pentode, the z. B. can be used for the time deflection in oscilloscopes.

Transistors can also be used in place of the tubes.

Claims (6)

Patent claims: 1. Circuit arrangement for generating time-proportional or stronger than time-proportional increasing control pulses for deflection levels in devices with cathode ray tubes, thereby characterized in that in the frequency-determining network of the deflection circuit a controllable capacitance via an ohmic one Resistance is charged or discharged, with the charging and discharging voltage the temporal Controls the instantaneous value of the capacity. 2. Circuit arrangement according to claim 1, characterized in that the controllable capacitance a capacitance diode or a voltage-dependent ceramic capacitor, for example based on barium titanate. 3. Circuit arrangement according to claim 2, characterized in that an adjustable bias voltage is in series with the time-varying on the two layers of the controllable capacitor. 4. Circuit arrangement according to claim 1 to. 3, characterized in that a fixed or adjustable capacitance is parallel to the controllable capacitance. 5. Circuit arrangement according to claim 1 to 4, characterized in that a counter or Positive feedback voltage in parallel or in series with the charging voltage for the controllable capacity and also has a controlling effect on this capacity. 6. Circuit arrangement according to claim 1 to 5, characterized in that several controllable capacities with different set time constants simultaneously or one after the other are in operation. 1 sheet of drawings 709 708/273 12.67 © Bundesdruckerei Berlin