DE1045570B - Generator to generate a saw-tooth-shaped current in an inductance - Google Patents

Description

Deflection coils are usually used to deflect the cathode ray in the picture tube of a television receiver used in which currents of a sawtooth shape, i.e. H. with a linear slow rising and a rapidly falling branch. For the horizontal deflection frequency of around 15 kHz, the deflection coils have essentially negligible inductive resistance small ohmic component, so that to generate a linearly increasing current an almost constant Voltage must be applied to them. Various circuits have become known for this purpose.

A sawtooth current generator is known which has a sawtooth-shaped inductance (deflection coil) Generates electricity and in which during the sawtooth trace a capacitor is present Voltage is applied to the inductance via a diode and at which the energy is lost through a a further inductance, in particular a transformer, connected, controlled tube covered which at the same time also takes over the control of the diode, whereby the anode DC voltage source for this tube is connected to the junction of the diode with the capacitor, and at which also the sawtooth return from a free half-oscillation of the inductance with the blocked Diode is still connected switching elements. The invention relates to such a circuit, in which the circuit containing the inductance, the capacitor and the switch diode is capacitive with the on the controlled tube is coupled to the inductance ("direct-drive" circuit).

It is also known in deflection circuits to use the high voltage for beam acceleration in the Cathode ray tube from the voltage peaks that occur in the inductance during return To produce rectification of the same and this inductance to increase the voltage as a transformer to train.

According to the invention, a generator for generating a sawtooth-shaped current in an inductance, in the case of a voltage across a capacitor during the sawtooth trace Diode is placed on the inductance and in which the energy losses through a to a capacitive with the Inductance-coupled self-induction connected, controlled tube can be covered at the same time also the control of the diode takes over (»directdrive« -circuit) and one with the self-induction autotransformer coupled winding is connected, characterized in that a further diode is provided, which from the beginning of the sawtooth trace to a connection between the Cathode of the controlled tube and a point of

Generator to generate

a sawtooth-shaped stream

in an inductor

Applicant:

Telefunken G. mb H.,
Berlin NW 87, Sickingenstr. 71

Willi Schröder, Ulm / Danube,
has been named as the inventor

Winding that occurs during the sawtooth trace

the cathode potential of the tube is to be maintained, and that this connection is interrupted again at the latest when the return starts.

It is known in the case of sawtooth generators, in addition to the voltage recovery diode, a current recovery diode to improve the energy balance, but this additional diode must be used in the known circuit with the voltage recovery diode be coupled. If the person skilled in the art would therefore apply the known circuit to the one available to him "To use direct drives circuit, he'd have to attach the additional diode to the deflection coils or one connect inductance coupled to this. In this case, however, it would not be that of the invention underlying task to be solved is to suppress self-oscillation of the self-induction. First of all, the circuit shown in Fig. 1, known as the "direct-drive" circuit is to be explained. In Fig. 1, 21 denotes the inductance of the deflection coils, parallel to which is the series connection of a so-called booster capacitor 22 and a diode 23. At the connection point of the diode anode with the booster capacitor is the positive pole 24 of the anode battery connected whose negative pole is grounded. When the sawtooth run-in, the diode 23 is open, so that the voltage on capacitor 22 is applied to the deflection coils and there is a linear rise in current generated. This circuit is controlled by a tube 25, in the anode circuit of which there is an inductance 26 and its grid over the capacitor 27 with a sawtooth-shaped or similarly shaped Voltage is controlled such that the tube 25 is blocked to initiate the sawtooth return will. The grid is over a grid leakage resistor

«09 697/467

Claims (1)

3 4 28 connected to earth. In this circuit, Fig. 3 shows a basic circuit diagram for explaining inductances 21 and 26 only capacitively with each other sintering this effect, which is not an embodiment coupled, so that the inductance 26 according to the invention is intended to represent. Here, a diode 40 at the end of the return flow, existing magnetic, is inserted into a circuit, as has already been explained with reference to FIG. 1, energy during the subsequent flow 5. The diode 40 is not, as in the previously described circuits, with its cathode on the anode of the tube 25 and with which there is a magnetic coupling between 21 of its anode via a resistor 41 on the battery and 26 through the diode 23. tension. In addition, its anode is obtained with a cone. The inductor 26 would therefore be capacitor 42 grounded. The resistor 41 is dimensioned in such a way that natural oscillations are carried out during the outward run, so that the forming on the capacitor 42 as long as the tube 25 is still in the blocked state. The voltage M _{42 is} smaller than that at the anode of the These natural oscillations are undesirable because they cause a series of disturbance phenomena to be stressed in the tube 25 towards the end of the sawtooth approach (M ₂₄ -M ₂₆ ). This is therefore necessary, causes can be, because they occur temporally during the opening of the tube 25 of the tube current of the forward line of the line. They are in the circuit 15 through the diode 23 and not through the diode 40, as shown in Fig. 1, through the losses in the flows. The voltage at the anode of the tube 25 has coil 26 and the capacitances 29 involved in it then have the curve shown in FIG. In time and 30 attenuated as well as through the tube 25, as soon as point E locks the tube 25, and the voltage to this is opened again. its anode rises sharply, then falls again until im Such a circuit is, as also in Fig. 1 20 instant F, the diode 40 opens and the anode chip is shown, mostly stabilized _{to the value M 40 with a special winding.} When opening the treatment 31 to generate a high voltage, tube 25, which can occur at a point in time H depending on the voltage peaks occurring sooner or later in the inductance 26 during the applied control voltage, the voltage at the anode of the tube rises 25 are stepped up to be in a diode 32 25 again to the value (M ₂₄ -M ₂₆ ), so that at the same time rectified and used as the acceleration voltage for point G, the initial state as in time E before the cathode ray. hand is. Ϊ7 ₂₆ is given by the inductive Fig. 2 shows the voltage curve at coil 26, voltage drop at inductance 26:
starting with the return line between time _. M.
point £ and time F. During the free half- 30 ^u ** ~ &'~dt'
The oscillation of the deflection circuit 21 also makes the where i is the anode current of the tube 25.
In this circuit, the energy recovered by attenuation to energy transfer from circuit 26, 29 to the circuit is negated in resistor 41, 33 (33 is the distributed coil capacitance of 21). In place of this resistance, any one across the capacitance 30 may be going on. At the time F 35 the energy-consuming part of the receiver opens the diode 23 so that the circuit with the coil 21 can be switched, e.g. B. the excitation winding opposite the natural oscillation of the circuit 26 and magnetic focusing coil. Such a circuit 29 is severely out of tune and therefore from this group can only be used to a limited extent, since the regulation has become practically independent. From time F z. As the current in the focusing coil always Rückab therefore has in a circle 26, 29 and 30 remaining 40 effects on the tension M ₄₀ and, therefore, some power characteristic oscillations states that the, by the \ ^r ER is not usable times. Losses in the switching means attenuated, take a course In the embodiment of the invention, as shown in dashed lines in Fig. 2 between Fig. 5, this disadvantage is avoided. Here is how times F and G are entered. This inherent - already mentioned - the diode 40 transforms to vibrations are not coupled to the anode of the tube 25 until the tube 25 45 is opened. In addition, a is completely dampened. This opening must be done before the part of the high voltage generation, anyway halfway between the times F and G, the last winding 31 of which is used. The connection point at the beginning of the next flyback period between the cathode of the diode 40 and the winding 31 is thus drawn. chosen that at it approximately earth potential or the Po according to the invention is in the so far described potential of the cathode of the tube 25 prevails. The anode and known circuit, the diode 40 in English, is accordingly connected to ground or the cathode of the tube 25 in the United States literature direct drive circuit. In this way, a further diode is provided which is connected to a current recovery in the sense that the anode of the tube 25 after the end of the sawing force that only a part of the tube current from the battery tooth return forces a fixed voltage. As a result 55 needs to be delivered, while the remaining part is achieved that the mentioned natural oscillations flows through the diode 40,
cannot take place, but that the written circuit leading to a fanning claim: Energy of the coil26 according to the point in time! ⁷ in a generator for generating a sawtooth Resistor connected to the diode destroys 60-shaped current in an inductance (21), at will. By means of suitable transformer coupling the one to one during the sawtooth trace With the diode, it can be achieved that the voltage in the coil capacitor passes through a diode 26 stored energy is diverted through the tube 25 and placed on the inductance and in which the vrird, so that a so-called power recovery energy losses through a to a capacitive with is achieved by saving energy, the otherwise 65 self-induction coupled to the inductance (26) could be achieved by a battery. Controlled tube (25) connected by this connection is covered point of view, the invention can be used as a combination, which also controls the nation takes over the well-known direct-drive circuit with diode (direct-drive circuit) and the current recovery system, which is also known per se, in which one with the self-induction (26) auto- diode to be viewed. 70 transformer-coupled winding (31) is switched, characterized in that a further diode (40) is provided from the beginning of the sawtooth trace to a connection between the cathode of the controlled tube and a Point of the winding (31), which is approximately at the cathode potential of the during the sawtooth trace Tube (25) is to be held, and that this connection is established at the latest when the return flow begins is interrupted again. Documents considered: German Patent No. 819 568. 1 sheet of drawings