DE1104995B - Circuit arrangement for generating a sawtooth-shaped voltage with an S-shaped superimposed component - Google Patents

Description

The invention relates to a circuit arrangement for generating a sawtooth-shaped Voltage, on which an S-shaped component is superimposed, with the aid of a connected as Miller integrator Discharge tube, the output electrode of the tube connected to the control grid via a capacitor is, the at least one step voltage to be integrated or a periodically interrupted DC voltage is supplied via a first resistor.

Such circuit arrangements can be used, inter alia, in television transmitters or receivers find, the generated S-shaped voltage, possibly after phase reversal, to control the output tube the vertical deflection circuit can be used. Such an output tube must if a television display tube with a large, relatively little curved screen, for example a 21- or 24-inch tube, Application is to send an almost S-shaped current through the deflection coils in order to achieve this ensure that the shift of the point of light on the screen itself is almost linear with time.

Such S-shaped deflection currents can also be used for camera tubes, for example of the supericonoscope type may be necessary to avoid the transport of electrons from the photocathode to the scanned To correct deformations resulting from the screen.

Circuit arrangements are known in which the desired S-shaped control voltage is thereby obtained becomes that from each of a number of sinusoidal voltages such a part is taken out, that an almost S-shaped tension remains. The different sinusoidal voltages are obtained in Relate to each other such a phase difference that the selected parts of a preceding and a subsequent sinusoidal voltage just join the part of the intermediate voltage.

According to other methods, sawtooth-shaped stresses are deformed with the help of filter networks, and still other methods use a non-linear tube characteristic using an additional one integrating network. Because the tube is controlled in the strongly curved part of the tube characteristic becomes, one half of the S and by adding one is obtained by means of the integration network Signal formed the other half.

However, all of these methods are cumbersome and also have the disadvantage that the curve obtained strongly deviates from the desired S-Foim.

Eei a circuit arrangement of the type mentioned above, it is possible, in a very simple way, the desired Obtain S-shape if, according to the invention, an integration network consisting of a resistor and a capacitor coupled to the output electrode of the tube and in parallel with the anode-cathode circuitry to generate

a sawtooth tension

superimposed with an S-shaped

component

Applicant:

NV Philips' Gloeilampenfabrieken,
Eindhoven (Netherlands)

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

Claimed priority:
Netherlands 14 August 1958

Peter Johannes Hubertus Janssen, Wouter Smeulers and Jan Abraham Cornells Korver,

Eindhoven (Netherlands),
have been named as inventors

Stretch of this tube is arranged and when the junction of the resistor and capacitor of the Integration network is also connected to the control grid of the tube via a second resistor.

Some possible embodiments of circuit arrangements according to the invention are based on the Figures explained in more detail below.

Fig. 1 illustrates known Miller integrator circuitry;

Fig. 2 shows a circuit arrangement modified according to the invention, while

3 and 4 show further embodiments of the Miller integrator connected as a Miller-Transitron oscillating oscillator represent.

In Fig. 1, 1 designates a discharge tube connected as a Miller integrator. The capacitor 2 is the Capacity needed to achieve the so-called Miller effect between the anode and the control grid of the tube is provided. If not, as indicated in Fig. 1, a pentode, but a triode is used, the stray capacitance that is always present between the anode and the control grid is sufficient for the circuit arrangement works as an integrator.

However, if the circuit arrangement is to be used as a relaxation oscillator, it is recommended as follows explains the combination with its so-called

103 577/256

3 4

Transitron circuit. In this case the mentioned stand is R ₄ , and μ-fold voltage amplification between

Stray capacitance too small, and it must be the capacitor 2 grid and anode and V _ao the initial voltage at the

be attached. Anode is at the moment when the integration

The Miller integrator can also be used with the help of Im-, whereby this V _{ao depends} on the direct current setting

pulse with the desired frequency and pulse duration 5 depends on the tube.

being controlled. In turn, a pentode is found. From the formula (1) it can be seen that the capacitor 2 turns, which is preferable in order not to unnecessarily influence the effect of the integrator due to the effect of the tube 1 on an integrator Factor A higher voltage is charged than the above-mentioned impulses would be possible for the safety grid or the anode without the presence of the tube 1,
be supplied to at the desired times io In the case described, in which a pentode tube to block or unblock the anode current. Which is used, however, when the anode-integrating voltage V _s is fed to the control grid of the tube 1 via a resistor 3 voltage to the so-called knee voltage V _ak. When this has fallen, the anode current in favor of the screen grid voltage, as indicated in Fig. 1, a jump voltage current from, so that from this moment on the anode is with the amplitude E and when the anode resistance 15 voltage almost no longer decreases. Because numbers are small in relation to the resistance 3, the anode 50 to 100 for the amplification factor A can be very well braced in the tube 1, is at a value E of, for example

/ _ ' 1 100 volts the voltage difference F _an - F _ffifc much smaller

a = ι a ₀ - A · L · l 1 - e - ¹² J (1) as the value A · E, so that only the lower part of the through

,,. . _{μR 1 ,,,, 7} ...,,,, 20 (1) specified charging curve is used, which is almost

given, where A = - = f- - ~ ie the gain factor Vi- u 2. λ.2. ■ 2. τ— h \ 1 ■, τ

^ss R _t + Ri is to be regarded as linear. For (1) can then also

of tube 1 with internal resistance Ri, anode resistance can be written approximately:

tt ² t ^{s Va} = ^Vao ~ ^Ä ' ^E AR ₅ Cz + ^Ä ' ^E YJzRjcJ ~ ^A ' ^E ~ 6ÄJR ~? Cj

or The desired S-shaped control voltage must be the

β . ^ Fulfill the formula for a third-degree curve.

V _a ^ V _ao p ~ r ~ · (2) Such a voltage can be achieved in that

³² the control grid of the tube 1 a new control voltage

This voltage curve is shown in FIG. 1. V ₆ 'is supplied through a resistor 3'. if

From (2) it can be seen that the voltage at the anode is a parabolic voltage of that voltage

of the tube 1 with some approximation using the formula shape

-4r- ä, x (3) 35

is, so can be with the help of the formula (3) in this

can be calculated, where at time t = 0 calculate the trap resulting anode voltage. This is

Anode voltage has the value F ₀₀ . given by

This could in principle be achieved by adding 45 resistor 3 'to the control grid of the tube 1

that three Miller integrators are connected one after the other, so that one at the anode of this tube

being, being between the second and the third tension yields with some approximation of the by

a phase inversion circuit is turned on and corresponds to the form determined by equation (5). This leaves

first a jump voltage F ₈ with the amplitude E can be demonstrated as follows:

is fed. The input voltage of the third inte- 50 When the control voltage F _{8 is} a jump voltage

grators would then be given by the equation (4), the anode voltage has a shape like it

given formula. is given by the equation (2). This chip

Such a circuit arrangement is, however, costly again by means of the network 5, 6 in

playful and complicated. Integrated by means of the circuit arrangement. Because the amplitude required in the end

according to the invention, which is shown in FIG. 2, the parabolic voltage at the control grid can be small

to achieve approximately the same result by being allowed to be, the integrating effect of this can also be achieved

the voltage taken from the anode of the tube 1 by means of the network can be regarded as almost ideal, see above

one of the resistor and the capacitor6 that with some approximation for the above

existing integration network again integrated capacitor 6 generated voltage can be written

will. The integrated voltage is thereby over a 60 can:

F ₀₆ = V ₁ ' = K ₁ J [Va ₀ ~ ^) dr = _Kl (v _ao t-- ££ -} + K _a , (6)

where K ₁ and K _{2 are} the constants determined by the network 5, 6 and the circuit arrangement. Substitution of (6) in (3) gives:
t

By using equation (5a): ^EK i j. _ jr

Ct =

2 R ₅ C ₂

and c = K,

2>

Voltage changes at the anode of the tube 1 with relatively low frequencies with respect to the frequency of the sawtooth voltage generated are not passed on, the capacitor 2 by results in equation (5). The controller can thereby replace two capacitors 2 _X and 2 ₂ , the capacitance value of 2 _{X being} large (e.g. six times) with respect to that of the capacitor 2 ₂ , while

take place that as the voltage V _s not a step voltage, but a positive DC voltage with a value of E volts, which is supplied by a voltage source 16, is taken. The safety gate or

the connection point of these capacitors is connected to earth via resistors 12 and 13. Also the

the anode of this tube is a pulse voltage ίο resistor 5 is divided into two resistors 5 _X and 5 ₂ . 15 supplied, whereby the anode current is unlocked during the The two thus generated branches of the trace of the sawtooth-shaped voltage shown in the figure and the bridge circuit are blocked by a variable during the return. While the resistor 14 is connected together. The capacitor 2 can discharge for the entire time delay time. constant of the resistors 5, 12, 13 and 14 and the The same result is achieved in that the * 5 capacitor 2 _X must be small with respect to the trace time Miller integrator according to FIG circuit is combined. Such a combination two or three times smaller.

is shown in FIG. 3. In this figure there is the This latter circuit is especially important when

The transit part from the screen grid and the catch grid, the control voltage taken from the resistor 13

of the tube 1, which are connected via a capacitor 7 to one another 20 of an end tube of the vertical deflection circuit in

are coupled, the screen grid being fed via the television transmitters or receivers,

stood 8 with the positive terminal of the not shown, a This end tube is namely usually about a

Voltage of F ₆ volts supplying voltage source coupled with the deflection coils supplied by the transformer

is connected, while the safety gate must be flowed through via the resistor an S-shaped current,

stood 9 with a variable tapping of a potentiometer

meter circuit is connected. The potentiometer - known to be the addition of an additional parabo-

circuit itself consists of a resistor 10, required on the scale component to the control voltage,

to which the variable tap is attached, and this is done by the fact that the capacitor 6 effective

Smoothing capacitor 11. Resistor 10 is a voltage across 5 ₂ and variable resistor 14

on the one hand with earth and on the other hand with the negative terminal 30 also the resistor 13 is supplied. Because it's for a

an also not shown, a DC voltage integration network is always required that in the

connected by voltage source supplying V _{r volts.} Frequency of the signal to be integrated the impedance of the

By means of this potentiometer circuit, the negative resistance is large in relation to that of the condenser

Voltage at the safety gate, and thus the natural frequency, is the impedance of the latter element in

of the Miller-Transitron oscillator. The transitron 35 is negligible in relation to that of the resistors,

partly concerned with the blocking of the anode current during For the equilibrium of the bridge it is sufficient if

the mentioned return time and determines the beginning applies:

of the outward run. R _5l · R ₁₃ = R ₅₂ · R ₁₂ .

It is true that a jump voltage cannot be assumed with this control, as was always the case with the 40 above calculations. The resulting error is, however, negligibly small, because if the anode voltage has a form as indicated by equation (5) or (5 a), the integration of this voltage with the aid of the network 5, 6 generates a Voltage across the capacitor 6, the shape of which, expressed in a formula, is also determined by the terms containing t ³ and t ^l . However, the coefficients of these terms are relative to the

Coefficients of the other terms are negligibly small, 50 pulses with greater amplitudes than in the above

so that the voltage on the capacitor 6 is fed to the anode almost parabo- mentioned case,

lic character. It should also be noted that the division of the

It should be noted that another advantage of the capacitor 2, the DC component in the circuitry described hereinabove, is that the network O ₁ , 5 _2, and 6 integrated signal lost coefficients of the various terms of Equation 55 are. However, because a direct voltage (5) can be set relatively precisely from the source 16, either through being supplied, this is harmless. Of course, changing the resistor 5 or by changing the must, however, the value of the equal value of F ₀₀ to be supplied by 16 (the latter depends on the voltage setting of this new situation, the tube 1). It is therefore always possible to use multi-lattice tubes such as hexodes and the desired S-shape with relatively high heptodes. There is the possibility of approximating this. Also the mentioned coefficients of allowing the return through the synchronizing pulses are in the case of FIG. 3 from the ratio between the conductors, in that these synchronizing pulses are fed to a resistor 5 and 3 'and in the case of FIG. 2 from the additional control grid. Ratio can also between the resistors 5, 3 'and 3 and be an additional screen grid as the output electrode of the value supplied from the voltage source 16 effectively 65, wherein the free end of the capacitor depending _X 2 DC voltage. connected to this screen grid. In this case

Another embodiment of a Miller-Transitron can control the voltage drawn from the anode

The relaxation oscillator is indicated in FIG. "of a phase discriminator can also be used

In order to remove the generated S-shaped voltage, synchronizing pulses are supplied. The this

to enable and also to ensure that 70 phase discriminator can take control voltage

With regard to the voltage supplied by the oscillator, there is no voltage difference across the resistor 14 so that changing 14 does not affect the amplitude or frequency of the S-shaped generated Exerts tension.

It should also be mentioned that the circuit arrangement with the aid of synchronizing pulses 17 with negative Direction sense can be synchronized. As indicated in FIG. 4, these can be the catching grid of the pentode are fed. It is also possible to use synchronizing

can be used, for example, to regulate the natural frequency of the Miller-Transitron oscillator when this a sawtooth voltage generated with line frequency.

Claims (2)

Claims: g 1. Circuit arrangement for generating a sawtooth-shaped voltage, which has an S-shaped component is superimposed, with the aid of a discharge tube connected as a Miller integrator, the The output electrode of the tube is connected to the control grid via a capacitor, the at least a step voltage to be integrated or a periodically interrupted DC voltage across a first resistor is supplied, characterized in that an integration network consisting of a resistor (5) and a capacitor (6), with the output electrode of the tube (1) coupled and arranged parallel to the anode-cathode section of this tube (1) and that the connection point of the resistor (5) and capacitor (6) of the integration network via a second resistor (3 ') also to the control grid the tube (1) is connected. 2. Circuit arrangement according to claim 1 for generating a control voltage for controlling the end tube of a vertical deflection circuit in television sets, characterized in that the integration network (5, 6) is received in a bridge circuit (S ₁ , 5 ₂ , 12, 13, 14), whose diagonal branch (14) can be changed, and that the parabolic component developed by the integration network (5, 6) via the diagonal branch (14) and via a resistor (13) of the bridge circuit (O ₁ , 5 ₂ , 12, 13, 14) of the End tube is fed. 1 sheet of drawings © 109 577/256 4.61