DE1090262B - Circuit arrangement for generating a saw tooth current through a coil - Google Patents

Description

The invention relates to a circuit arrangement for generating a sawtooth current through a coil by means of a discharge tube, one of which is the tube periodically unlocking voltage is supplied and in its output circuit the series connection of a primary winding a transformer to which said coil and a series saving diode are coupled, and a capacitor assigned to the series saving diode circuit.

Such circuit arrangements are used, among other things, in television transmission and reception systems. The field generated by the sawtooth current is used to deflect the electron beam in a horizontal direction used in camera or picture tubes.

Especially when an excellent linearity of the generated current is desired, one comes across the difficulty that the coil through which the sawtooth current flows is not a pure self-induction, but rather also has a certain ohmic resistance.

It is known per se that it is consequently not sufficient if the circuit arrangement above the The voltage generated by the coil is of a rectangular type, but rather a sawtooth voltage should be applied to this rectangular voltage can be added.

In a circuit arrangement of the type mentioned, this is achieved in a simple manner if, according to FIG Invention with the end of the series saving diode facing away from the transformer, a linearization capacitor is connected, via which a circuit arrangement when the tube is unlocked

to generate a sawtooth current

through a coil

Applicant:

NV Philips' Gloeilampenfabrieken,
Eindhoven (Netherlands)

Representative: Dipl.-Ing. EE Walther, patent attorney,
Hamburg 1, Mönckebergstr. 7th

Claimed priority:
Belgium 17 July 1958

Teunis Poorter and Josue Jean Philippe Valeton,

Eindhoven (Netherlands),
have been named as inventors

which is periodically unlocked by means of the control voltage 2 and, together with the series saving diode 3, causes that coupled with the transformer 4

Sawtooth voltage is generated. According to a further coil 5, a sawtooth current flows. As is well known, is too Forming the invention, this can be achieved by using the primary winding of the transformer 4 for this purpose

in series with the capacitor 6 assigned to the circuit of the series energy-saving diode in the anode circuit of the tube 1. The value from tip to tip of the tube 1 through

that the linearization capacitor with the tube unlocked a constant current flows through it.

It should be noted that in the case of a sawtooth generator

with a series saving diode circuit is known per se, 35 flowing anode current i _a and the series saving outside the series saving diode circuit a special diode 3 flowing through current% is to be attached by the VerDiode, which on the one hand to the transformer
and on the other hand over one of a resistance over

bridged capacitor is connected to earth. The ratio between the number of primary turns%, the number of secondary turns W ₂ and the number of tertiary turns n _{3 of} the transformer 4 is determined.

the voltage on the capacitor is independent of the 40 In the present example is an autotransformer run of the sawtooth current constant; has been used by setting the, with the cathode of the series saving

Voltage, the sawtooth amplitude can be changed.

Through this circuit, the high voltage generated by rectification during the kickback should be in their

Amplitude can be stabilized. The linearity of the saws 45 lungs are galvanically isolated from each other, for use

the current of the tooth is not improved. dung can come. The way in which the diode 3, the

Coil 5 and capacitor 6 are connected, should be matched with three separate windings.

In one possible dimensioning of the transformer 4, the current ia is kept essentially constant when the tube 1 is unlocked, and the anode current i _a increases linearly

diode on the secondary winding and the coil 5 on the Tertiary development lies. It is clear, however, that an ordinary transformer, in which these three windings

Some designs of circuit arrangements according to the invention are based on a drawing, for example explained in more detail.

Fig. 1 shows a first embodiment; Fig. 2 is used for explanation, and the

FIGS. 3 and 4 show further developments of the circuit arrangement according to FIG. 1.

In Fig. 1, 1 denotes a discharge tube as a function of the time up to its maximum value, after which both i _a and ia are suppressed during the ramp-down time of the sawtooth current. In this

009 610/269

3 4

In the event that the various currents can be used accordingly, a voltage is generated which corresponds to that of the series

Fig. 2 are shown. Saving diode 3 current flowing through it is proportional to ig.

In this figure everything is transferred to the tertiary winding. The voltage generated across this resistor 9 is

The transformer is now assumed to be ideal via the capacitor 10 and the resistor 11

is taken. As a result, the anode current 5 reaches the control grid 12 of a discharge tube 13,

„ _R ,», jj -rv- j χ · tir ί whose anode circuit contains a transformer, whose

a value - - ■% _a and the diode current a value -,. ·,, -, -, .., **> ■ <_ · ,, τ- jj τ. ·

% of the anode of the tubes 13 facing away from the end of the Pn-

ih ■ ti7 -χ · j. j jc- lcj TJ j ox märwickung 14 with the positive terminal of a not

- ^ - ·%. Furthermore, the current passing through the coil 5 is, ,,, ^to _o . * ,,,,. ,,.

% ^a ^ - the supply voltage source shown is connected to the

with i _s , the negative peak value of this current with i _S2 io delivers a voltage of F ₆ volts. Between the mentioned and the positive peak value denoted by i _Si. In this th positive terminal and the anode of the diode 3 is the case, it can be calculated that the ratio between the secondary winding 15 of this transformer. The number of primary windings n _x and the number of self-induction coefficient of the secondary winding 15 is the secondary winding n ₂ selected so large that the said coil by flowing _n j ι r JL ι ¹ S current does not change its size substantially - - = - ^ - · - J e ² ^ + 1> capable, so that the coil 15 ^{behaves as a current source n} 2 ^l ag 2 [J. Because in this case the dimensioning of the transient should correspond to where Hg is the series energy-saving diode 3 transformer 4 such that the current% decreases during the setting current, i _ag the ramp-up time of the sawtooth current flowing through the tube 1, the current Q must also be the Quality of the overall circuit in the anode circuit of 20 the current it decrease during this time. This is achieved by representing the tube and that the tube 13 by flowing ■ _ * _ stream with the occurring across the resistor 9 - ^ i- = e ^ ^2. Voltage is controlled. If the current ig, ^is2 decreases, the voltage across resistor 9 will also decrease,

As stated at the beginning, the coil 5 is not a pure self-25 and this voltage change is caused by the tube 13

induction, but it also has a certain ohmic and the coil 14 which is inductively coupled to the coil 15

Resistance, so that it must be ensured that in addition to the current i _{t is} transmitted, so that this also decrease

the described control by means of the tubes 1 and 3 is. With correct dimensioning of the circuit arrangement

nor a sawtooth voltage generated across the coil 5 can be ensured that the decrease of i _t der

corresponds to the 30 of ig occurring at the resistance of the coil 5, so that the differential current it - ia

Voltage loss will be constant when the sawtooth current runs. With this the aim has been achieved,

balance. so that again a sawtooth voltage across the condenser

For this purpose, according to the invention, a linearizer 7 will appear.

Sierungskondensator 7 between the anode of the diode 3 It should be noted that the resistor 9 is relatively and earth arranged. If it is ensured that 35 should be small, to influence the rest of the circle to prevent this capacitor 7 when the sawtooth current continues. A correct value of this resistance is a constant current flows through it becomes about 30 Ω. The cathode of the tube 13 can also be connected to the a connection point of 6 and 9 is connected via this capacitor during the run and that Sawtooth voltages occur, which are connected to earth via the continuously conductive control grid of this tube. because Diode 3 to the transformer 4 and consequently the 40 changes the phase of the potential changes in the control grid coil 5 is fed. circle of the tube 13 by this modified control

If the currents i _a , ig, and i _s had reversed their shape accordingly, the connections of the coil 14 must also be

Fig. 2, with the tube 1 unlocked, the current would be ig, im swap.

essentially constant, so that in this case it is a further development of a circuit arrangement

would suffice to ensure that the current 45 of the invention is shown in FIG. In this figure, in

source 8 supplied current it is essentially constant, the corresponding parts as much as possible the same

to achieve that the capacitor 7 flow through reference numerals, the transformer 4 is such

ßende current i _t - ig, is also constant. The currents measure that the currents i _a , ig and i _s accordingly

source 8 must therefore look like a voltage source with high Fig. 2. By means of the coil 15, accordingly

Internal resistance so that the change in the load 50 Fig. 3 ensures that the current it is also constant,

for the source 8 there is no change in the output from this source, so that if it weren't for the non-linearities of the tubes 1

delivered current. and 3 or the aging of these tubes the constancy of the

With this type of control, however, the yield of the total current is impaired, the aim pursued, namely a

The circuit arrangement is very small, because the current i _t - ig, which is constant for the diode, would now be achieved without further ado.

,, ". _n , _, xxj - »τ · ι _x% · 55 The latter evil is through the attachment

current flowing through always the maximum value - ^ -. «,“. "^ _{1,. ,, Ίί} - .. _n ^ö

n ₂ ^{s2 of} a negative feedback loop. This counteraction must, whereby the peak value of the anode coupling circuit consists of a discharge tube 16, the current is unnecessarily increased. It is therefore better to have a resistor 25 in the cathode circuit. The resistor 25 gradually decreasing the diode current ig during the run-out is to be left in series with the capacitor 7 in such a way that the anode current is also switched less than in 60 that, if due to non-linearities or due to FIG - aging of the tubes called the power it - ig not processing arrangement benefit. is completely constant, the mentioned negative feedback

A circuit arrangement in which the aforementioned circuit will correct this inconsistency. To this end

The goal is achieved, and despite this the current i _t - ig at is the tube 16 in the input circuit of the tube 1

The trace of the sawtooth current remains constant, is in 65 input circuit consists of a charging capacitor 18

Fig. 3 shown. and a peak-forming device connected in series with it

In this figure is in series with the capacitor 6 resistor 19; this charging capacitor 18 is over

a relatively small resistor 9 was added, a resistor 20 charged during a time that

and the cathode of the tube 1 corresponds to the connection of the sawtooth current. To this

point between 6 and 9 connected. At the resistor 9 70 purpose is the switch 21 during this trace time

I 090

open and closed during the ramp-down time of the sawtooth current, as a result of which the capacitor 18 is able to discharge quickly via the switch 21 and the relatively low peak-forming resistor 19. The tube 16 is now connected in parallel to the capacitor 18 and to the resistor 19 and, in accordance with the voltage occurring across the resistor 25, influences the speed at which the capacitor 18 is charged. The voltage generated as a result of the total charging current via 18 and 19 is fed to the control grid of the tube 1 via the capacitor 22 and the resistor 23, so that, because the voltage via the capacitor 18 can be regulated by means of the aforementioned negative feedback circuit, the current i _a and consequently the current ig, will be such that i _t -% will be essentially constant when the sawtooth current runs.

It should also be noted that the switch 21 can be a discharge tube, which with the help of elsewhere can be controlled from the circle-related pulses.

The cathode circuit of the tube 16 consists of the resistors 24, 25 and the capacitor 26 24 and 26 provide the required negative bias; the resistor 25 is the actual negative feedback resistor. By means of those connected to the control grid of the tube 16, mounted on the resistor 25 Tapping, the degree of negative feedback can be set.

A useful mode of operation of the circuit arrangement according to the invention has been obtained when the self-induction coefficient of coil 15 had a value of 5 henry and the capacitance value of the capacitor 7 was about 20,000 pF.

Claims (6)

Claims. 1.Circuit arrangement for generating a sawtooth current through a coil by means of a discharge tube, to which a voltage that periodically unlocks the tube is fed and in its output circuit the series connection of a primary winding of a transformer, with which the said coil and the series saving diode are coupled, as well as a series saving diode circuit assigned Capacitor, characterized in that a linearization capacitor (7) is connected to the end of the series saving diode (3) facing away from the transformer (4), via which a sawtooth voltage is generated when the tube (1) is unlocked. 2. Circuit arrangement according to claim 1, characterized in that the linearization capacitor (7) is traversed by a constant current {it -%) when the tube (1) is unlocked. 3. Circuit arrangement according to claim 2, characterized in that the current source (8) consists of an inductance (15) with a relatively large self-induction coefficient, which is arranged between the series saving diode (3) and the positive terminal (+ Vb) of a supply voltage source. 4. A circuit arrangement according to claim 3, characterized in that the end remote from said primary winding of the capacitor (6) associated with the series saving diode circuit via a relatively small resistor (9) is connected to the negative terminal (ground) of the supply voltage source . Discharge tube (1) is connected to the junction of this capacitor (6) and this resistor (9) and that the voltage occurring across the resistor (9) is fed to a control electrode (12) of a second discharge tube (13), the anode of which is supplied via a the said inductance (15) inductively coupled second inductance (14) is connected to the positive terminal (+ Vb) of the supply voltage source. 5. Circuit arrangement according to claim 3, wherein said transformer is dimensioned such that the ratio between the number of turns M _{1 of} the primary winding and the number of turns n _{2 of} the secondary winding, to which the Reüienspardiode is connected, through is given where i $ _{g is} the mean current passing through the series energy-saving diode, i _{ag is} the mean current flowing through the discharge tube and Q is the quality of the overall circuit in the output circuit of the discharge tube, characterized in that the linearization capacitor (7) has a resistor (25) with the negative terminal (ground) of the supply voltage source is connected and the voltage occurring across this resistor (25) is fed to a negative feedback circuit (16), the output of which is coupled to the input circuit of the discharge tube (1). 6. Circuit arrangement according to one of the claims 3 to 5, characterized in that the self-induction coefficient the first-mentioned relatively large inductance (15) about 5 henry and the capacitance value of the linearization capacitor (7) is about 20,000 pF. Considered publications:
German interpretative document No. 1 001 780. 1 sheet of drawings ©; 009 610/269 9.60