DE1080601B - Circuit arrangement for generating a voltage that increases linearly over time - Google Patents

Description

LIBRARY

OF THE GERMAN

PATEfJTAKTES

The invention relates to a circuit arrangement which is used to linearly increase with time Voltage, and the a capacitor, a DC voltage source and a resistor across the the capacitor is charged.

Such circuits are mainly used in television broadcasting and receiving systems in which a cathode ray tube is used. Devices are required for controlling the scanning movement of the cathode ray beam a triangular current or voltage produce. It is desirable in such systems that the control voltage increase linearly with time. There are already known circuit arrangements for generating a triangular current or a triangular voltage, which have a capacitor, a DC voltage source and a simple resistor across which the capacitor is charged by the DC voltage source, while a discharge tube connected in parallel to the capacitor serves to periodically discharge the capacitor.

Such a known device for generating a triangular voltage is shown in Fig. 1 of the drawing, in FIG. 1 a voltage source, 2 a capacitor, 3 a discharge tube and 4 a simple ohmic one Resistance through which the capacitor is charged is called.

The effect of such a circuit is as follows:

The capacitor 2 is from the voltage source 1 via the resistor 4 with a by the size of the Resistor 4 and capacitor 2 conditionally charged until the ignition voltage of the discharge tube 3 is reached or until, what is common in television systems, on a grid of the tube 3 (not drawn) a voltage surge occurs; At that moment the capacitor suddenly discharges and the charging starts again.

However, the instantaneous value of the voltage occurring across the capacitor 2 increases during the charging time only increases linearly with time if the charging current of the capacitor 2 is constant. It is for this purpose already known to charge the capacitor 2 via a constant current resistor, which is saturated by a Two-electrode tube, formed by a lattice tube or a pentode.

When using such resistors are batteries that have a variable voltage with respect to own the earth and therefore may not be earthed either directly or capacitively, indispensable. Further the capacities that these batteries have in relation to the earth form part of the frequency the generated oscillations determining circle, so that the frequency that can be achieved with the circuit can be reduced.

Circuit arrangement for generation

one that increases linearly over time

tension

Applicant:

Philips Patentverwaltung GmbH,
Hamburg l _r Mönckebergstr. 7th

Claimed priority:
Netherlands from. April 18, 1935

(N39243VIIIc / 21g)

Requests after. Law No. 8 AHK are placed and before the

Arbitration Commission for Goods, Rights and Interests

pending in Germany

It has already been proposed, in circuits of the type mentioned above, in which the capacitor is charged via a pentode or screen grid tube, to eliminate deviations from the linear voltage rise of the capacitor voltage due to the presence of other switching elements in parallel with the capacitor by selecting a suitable voltage from the capacitor derived compensation voltage is pressed onto the control grid of the charging tube.
In contrast, the present invention relates to a circuit in which the capacitor is charged via a simple, ie non-current-constant resistor, and its purpose is to compensate for the voltage rise of the capacitor voltage which is not precisely linear in time as a result.

This is achieved according to the invention in that in the charging circuit in series with the charging resistor and of the charging current source is at least a part of the anode impedance of a discharge tube to which one of the voltage derived from the capacitor voltage occurs, which is equal to the capacitor voltage.

For the sake of completeness it should be mentioned that it is already known that due to the presence of Not current-constant switching elements occurring distortions of a sawtooth-shaped breakover oscillation to compensate by means of a network.

In one embodiment of the circuit according to FIG Invention, the voltage derived from the capacitor is applied to the anode circuit of the last of an even number of cascade connected discharge

00Ϊ 507/271

3 4

tubes removed from which the over! the capacitor increases in a perfectly linear manner with time. This stems from

emerging voltage is supplied. due to the fact that the resistance 7 is

The voltage derived from the capacitor cannot be chosen to be very high depending on the tube 6

likewise the anode circuit of the last one can be odd. The current flowing through the resistor 7 is in

Number of connected in cascade connection 5 in this case no longer used in relation to the charging current

Charge tubes are removed if an odd one is negligible. This drawback can according to the invention

Number of these tubes formed by a multigrid tube by such an adjustment of the point 13 on

whose electrode voltages are set in such a way, resistor 12 is eliminated that the in the charging current

that there is a voltage in the anode circuit of the multigrid tube. . . . " ., /. r, \,. ,. .

occurs that multiplied by the voltage supplied to the grid ₁₀ ^{circle TOrksame} voltage by (l + - ^)

is in phase. ·. ;. - capacitor voltage is the same, where R _{1 is} the size of the

A more detailed discussion follows on the basis of the drawing, resistor 4 and R ₂ the size of resistor 7

in which FIGS. 2 to 4 denote some embodiments of FIG. That with this setting of point 13

Circuit arrangements according to the invention show. the capacitor voltage increases linearly with time,

In Fig. 2 there is a circuit for generating a to 15 follows from the following equations:

triangular ^ _ necessary for tactile purposes in television systems.

voltage represented by a capacitor 2, a DC + ^e i2 - ^ - ^ ₁ + e ₂ , (1)

Voltage source 1 and a resistor 4, _e __ ^ ^> ιγ,

Via which the capacitor 2 is connected to the DC voltage 222 ..

source 1 is charging. The capacitor discharges 20 j _. j _i_ j π \
intermittently via a discharge tube 3, the

Grid intermittent pulses are fed. The above where E is the voltage of the DC voltage source 1, i _x

the capacitor 2 occurring voltage is over a the charging current of the capacitor 2, i ₂ through the

Capacitor 5 is fed to a discharge tube 6, current flowing between grid discharge resistor 7, i the

see their grid and cathode a discharge resistor 25 through the resistor 4 flowing current, e ₂ the voltage

stand 7 lies. The in the anode circuit of the tube 6 via a capacitor 2, e ₁₂ the voltage across the im

Resistor 8 occurring voltage is expediently charging circuit lying part of the resistor 12, R ₁

fed to the baffles of a cathode ray tube. the size of the resistor 4 and R ₂ the size of the

In order to ensure that the grid discharge resistor 7 is represented by the capacitor 2,

As the voltage increases linearly with time, it becomes 30 - Equations (1), (2) and (3) can be derived: voltage occurring in the anode circuit of the tube 6

a grid capacitor 9 and. a derivative resistor E - \ - e ₁₂ = (^ ₁ + J ₂ ) A ₁ -j- e ₂

stood 10 applied to the grid 11 of a tube in whose ° & ^eT

The anode circuit has a resistance, from which a point 13 _i IR ₁ Λ

with the end 35 ⁺ ^ ¹² ~ j * ^{1 x +} ^ ² \ R ^ ⁺ /

of the resistor 4 is connected. With the described -

The circuit is in the charging circuit, which is the voltage actual in this equation during the charging time e ₂

source I ₁ which also acts as an anode voltage _{source for / B 1} . ₁ \ ·, ■, _T ·,, ·, _T7 - · _{,, o}

j -n-il cj ^^ j ^ jj ττΓ-jij λ j -? γ- + 1 = #! <>, then the charging current of capacitor 2 is used for tubes 6 and 11, and resistor 4 and \ R ₃ j "

contains the capacitor 2, that part of the resistor 40 is constant during this period, so that the voltage level 12, which between the point 13 and the positive of the capacitor increases linearly with time.
Pole of voltage source 1 is. The point 13 is invented. Another measure chosen according to the invention in such a way that the voltage caused by the resistor 7 caused by the part of the resistor 12 occurring via the above-mentioned equation can be met by the deviation, is that the capacitor 2 occurs Voltage is the same. 45 a point between the ends of the lattice

It is achieved with the circuit described that line resistance 7 is connected to a point,

the voltage occurring across the capacitor while its voltage is the voltage occurring at the grid of the tube 6

the charging time increases linearly with time. This makes voltage equal and in phase with it. The one who

explain as follows: stand 7 current flowing through remains in in this case

Equation 50 applies to the charging circuit at every instant zero and can therefore determine the charging current

of the capacitor 2 does not affect very much. aside from that

L · - \ - e _1% = e ₂ - \ - e ₄ , the capacitor 5 can consequently be much smaller

in the E, the voltage of the DC voltage source 1, e _{2 can be} selected without affecting the shape of the curve which the

the voltage occurring across the capacitor 2, e ₄ the instantaneous value of the voltage as a function of time.

The voltage across the 55 is via the resistor 4 and e _{12 and is thereby influenced.} The one between the

Part of the resistor 12 lying in the charging circuit at the ends of the point of the discharge resistor 7

designated. In this equation, the voltage to be supplied during the charging time can be one of the anode circuits

e ₂ = e ₁₂ , ie if there is a voltage in the charging circuit, discharge tubes are taken from the circuit,

sam, which is equal to the capacitor voltage and with it. An embodiment of a system for generating

in phase is what by a correct choice of the number 60 of a triangular voltage, in which the said measure

of the stages and connected downstream of the capacitor 2 is shown in FIG. 3. In this figure

can be achieved by setting the point 13 is between a point 14 of the resistor 7 and

so the voltage e _{4 is applied} across the resistor 4 while the cathode of the tube 6 is a voltage that the

this period constant. The capacitor is located in this between the grid and the cathode of the tube 6.

If charged with a constant current, and 65 stepping voltage is the same and with this voltage in

the voltage across the capacitor 2 increases as a result of the phase, since the point 14 has a blocking capacitor 15

its increasing linearly with time. with the one connected to the anode circuit of the tube 11

■ With the circuit described, however, it is possible for the end of the resistor 4 to be connected. The circuit

that by the presence of the condensate corresponds otherwise completely to that shown in FIG

■ tor 5 connected resistor 7 the voltage not 70 circuit. An advantage of the latter measure for

Compensation for the influence of the grid leakage resistor 7 with respect to the former consists in that it is independent of the size of the resistor 4, while the former measure of the size of the Resistance 4 and therefore depends on the amplitude of the vibrations to be generated.

In Fig. 4 a circuit is shown which is useful for controlling the scanning movement of a cathode ray beam a cathode ray tube with electrostatic control applied for television transmission and reception purposes will.

With this circuit, a triangular voltage is generated with the help of a voltage source 1, one Capacitor 2, a resistor 4 and a discharge tube 3, to which the synchronizing pulses are supplied which cause the capacitor 2 to discharge. The triangular voltage occurring across the capacitor 2 is fed to the cascaded tubes 6 and 11 in a known manner. That The grid of the tube 11 is connected to such a point of the output circle of the tube 6 that the between the grid and the cathode of the tube 11 occurring triangular voltage of the voltage that the grid of the tube 6 with respect to the cathode, is equal and in phase opposition with this voltage. As a result, it occurs in the output circuit of the tubes 6 and 11 via the resistors 8 and 12 voltages which are equal to each other and are in antiphase with each other. The ends of the resistors 8 connected to the anode of the associated tube and 12 are each associated with one of the baffles 16 and 17 serving to control the cathode ray beam Cathode ray tube, optionally via a grid capacitor and a leakage resistor, connected. In the circuit described, the voltage in the center plane between the deflection plates is constant, like this is desirable to avoid distortion of the received image in cathode ray tubes.

In order to achieve in the circuit described that the voltage between the plates 16 and 17 is linear with As time increases, a voltage is drawn from the anode circuit of the tube 11, which is the capacitor voltage . is equal to and in phase with it, because point 13 of the Resistor 12 is connected to the end of the resistor 4 remote from the capacitor 2. The influence of the In this circuit, resistor 7 can, if desired, be canceled by setting point 13 in this way that the voltage between this point and the one with the positive pole of the DC voltage source connected end of resistor 12 is equal to the span multiplied by the factor (- ^ - + 1]

V - "- 2 /

Tiung of the capacitor 2 is. However, it becomes expedient a voltage equal to the voltage occurring between the grid and the cathode of the tube 6 and is in phase with it, between a point of the grid 7 and the cathode of the tube 6 ■ applied by the fact that the capacitor 2 remote The end of the resistor 4 is connected to a point of the grid discharge resistor 7 via a capacitor 15 will.

Another embodiment of the circuit according to the invention consists in that the capacitor voltage derived voltage is taken from the anode circuit of a multigrid tube, which is connected via a capacitor occurring vibrations are supplied and their electrode voltages are set in such a way that that the voltage occurring in the anode circuit is in phase with the voltage applied to the grid.

In the embodiment described, a DC voltage source can also be used to charge the capacitor 2, which does not act as the anode voltage source at the same time for the tubes connected behind the condenser. The one away from the condenser In this case, the end of the resistor is connected to point 13 of the anode circuit via a blocking capacitor connected, from which the voltage derived from the capacitor voltage is taken. To do it too prevent the DC voltage source from which the capacitor 2 is charged, a short circuit for the equalizing voltage forms, it is necessary that in the supply circuit in series with the DC voltage source high resistance.

Claims (6)

Patent claims: 1. Circuit arrangement for generating a voltage that increases linearly over time on a capacitor which is charged from a DC voltage source via a simple, non-controlled resistor, characterized in that at least part of the anode impedance of one in the charging circuit in series with the charging resistor and the charging current source Discharge tube is at which a voltage derived from the capacitor voltage occurs, which is equal to the capacitor voltage or of such a size that the voltage across the capacitor increases linearly with time. 2. Circuit arrangement according to claim 1, in which the voltage occurring across the capacitor is above a grid capacitor is fed to a discharge tube with a leakage resistance, characterized in that, that from the capacitor voltage 1 + -— ■] multiplied capacitor voltage, where R _{1 is} the size of the charging resistor and R _{2 is} the size of the grid leakage resistance, 3. Circuit arrangement according to claim 1 or 2, characterized in that the capacitor voltage derived voltage to the anode circuit of the last of an even number of cascaded connected discharge tubes is removed, which the occurring through the capacitor Voltage is supplied. 4. Circuit arrangement according to claim 1 or 2, characterized in that the capacitor voltage derived voltage is taken from the anode circuit of a multigrid tube whose Electrode voltages are set so that the voltage occurring in their anode circuit with the Capacitor voltage is in phase. 5. Circuit arrangement according to claim 1, 3 or 4, in which the voltage occurring across the capacitor is fed via a grid capacitor to a discharge tube with leakage resistance, thereby characterized in that a point between the ends of the grid leakage resistance with is connected to a point in the circuit, the voltage of which changes in the same way as the Voltage at the end of the grid drain resistor connected to the grid. 6. Circuit arrangement according to claim 5, characterized in that a between the ends of the Grid leakage resistance point with the end of the resistor facing away from the capacitor connected through which the capacitor is charged. 1 sheet of drawings