FI59316B - REGLERINGSKRETS FOER EN HORISONTALAVLAENKNINGSGENERATOR - Google Patents

Description

RSP1 M <ii) MONTH, LUTUS <UL, tA ,, u 593-1 g

Ml 1 J '' UTLAGGNINOSSKIUFT ° 7 J ισ C μ »Patent ny tn ne tty W 07 1931 Patent n-cdlelat ^ T '^ (51) Kv.ik.3 / iBt.ci.3 H CW- N 3/18 FINLAND —FIN LAND (21) P «.nttihtk * rmi * -P * t.nt * n *« kn) nt 7801 + 15 (22) Hakemlipihrl - Anrtknlnpdag 08.02.78 '* (23) AlkupUvi - GlMghaudag 03.01+. 73 (41) Tullut JulklMksI - Bllvlt offwKlIg 08 02 78

Patent · and rakl.tarlh.IHtu. Nihuvitcip * ™,. month. ^ n date. - *

Patant- och ragiataratyralMn 'Aniaktn uti «(d och uti.ikrift« n pubik «nd 31.03.81 (32) (33) (31) Pyydetty atuolkwit — S« glrd prlorltat 05-01 + .72

England-England (GB) 15576/72 (71) RCA Corporation, 30 Rockefeller Plaza, New York, N.Y. 10020, USA (72) Wolfgang Friedrich Wilhelm Dietz, New Hope, Pennsylvania, USA (7 ^) Oy Kolster Ab (5I +) Control circuit for horizontal deflection generator - Regleringskrets för en horisontalavlänkningsgenerator (62) Divided separated from application 1023/73 (Publication 59315) -Avdelad fran ansökan 1023/73 (utläggningsskrift 59315) This invention relates to a control circuit for a horizontal offset generator of a television receiver.

It is desirable to adjust the operating voltage of the horizontal deflection circuit of the television receiver to supply constant energy to the horizontal deflection windings during different deflection periods. Variations in the supply voltage change the magnitude of the sweep current in the deflection winding and cause undesirable changes in the width of the image. In addition, it is common to generate a high voltage on the picture tube from the horizontal deflection circuit by rectifying the return pulses generated by the horizontal output transformer during the return time of each deflection interval. Variations in the supply voltage change the energy of the return pulse and thus the high voltage, causing variations in the brightness of the image and further changes in the width of the image. In addition, the operating voltage for other parts of the receiver, such as the video and audio stages, can also be formed from a horizontal deflection circuit, and it is desirable that these voltages are also regulated. Of course, it is known to use separate voltage regulators in booster and other circuits, but the use of these is expensive and increases the complexity of the receiver. In addition, for economic reasons, it is desirable to rectify the AC mains voltage without using a power transformer to raise the mains voltage to a sufficiently high level for the supply voltage of the deflection circuit. The present invention relates to a circuit for raising and adjusting a rectified AC voltage for use in a deflection circuit of a television receiver.

According to the invention, there is provided a control circuit for a horizontal deflection generator having a direct current source, a sensing circuit connected to a voltage source representing the energy level in the deflection generator to provide a control signal, an inductance connected to the horizontal deflection generator and a in series with a direct current source and an inductance for supplying a driving current to a horizontal deflection generator, and characterized by the features mentioned in the characterizing part of claim 1.

A more detailed representation of a preferred embodiment of the invention is set forth in the following description and the accompanying drawings, in which: Figure 1 is a schematic representation, partly in the form of a block diagram, of a deflection system according to the invention; Fig. 2 is a graphical representation of the DC voltage at two points in the circuit of Fig. 1 with respect to the mains voltage; Figures 3A-3G are normalized waveforms obtained at various points in the diagram of Figure 1, and Figure 4 is a schematic representation of another implementation of a control circuit in accordance with the invention.

Figure 1 is a schematic representation, partly in block form, of a deflection system according to the invention. With the exception of the control circuit, which will be shown later, the horizontal deflection circuit is of the return type, as is the circuit disclosed in U.S. Patent No. 3,452,2 * 44. This circuit includes a changeover switch 11 comprising a silicon controlled rectifier (SCR) 12 and a reverse damping diode 13 connected between the winding 27a of the input choke 27 and ground. To determine the operation of the deflection circuit, the other end of the winding 27a can be considered to be connected to a positive DC voltage source. The commutation switch 11 5931 6 is connected by means of a commutation winding 22 and a capacitor 23 to a line switch 14. The line switch 14 comprises an SCR 15 and a damping diode 16 connected in the opposite direction.

Capacitor 24 is connected between the coil 22 and the junction of capacitor 23 and ground. The line switch 14 is connected to ground through the series connection of the horizontal deflection coil 17 and the S-correction capacitor 18 and to the ground via the primary winding 19a of the horizontal output transformer 19 and the DC blocking capacitor 20.

The secondary or high voltage winding 19b in the transformer 19 generates relatively high amplitude reset pulses during the reset time of each deflection period. These pulses are directed to their high voltage multipliers and rectifier circuit 21 to generate a high DC voltage of the order of 27 kilovolts for use as an acceleration voltage of a television picture tube (not shown).

The horizontal oscillator 25 is connected to the control electrode of the commutating SCR and generates a pulse during each deflection period shortly before the end of the line slot to make the SCR 12 conductive to start the commutation slot. The waveform circuit 26 is connected to the output of the input choke coil 27a and to the control electrode of the line SCR 15 to generate a signal that allows the SCR 15 to be conducted during the second half of the line slot.

In the control section of the deflection system, the AC mains voltage is rectified by a rectifier diode 28 and filtered in a filter circuit 29. The DC voltage obtained from the filter circuit 29 is connected by means of a diode 30 and a current limiting resistor 31 to a second terminal of the charging capacitor. The connection point of the resistor 31 and the capacitor 32 is connected to one end of the winding 27a of the input choke 27 to supply the operating DC voltage to the deflection circuit.

The other end of the winding 27b of the input inductance 27 is connected via the inductance 33 to the anode of the voltage control SCR 34. The cathode of the SCR 34 is connected to a capacitor 32. The junction of the coil 27b and the inductance 33 is connected to the base of the control transistor 35 by a capacitor 38, a resistor 37, a resistor 39 and a resistor 40. The emitter of the transistor 35 is connected to the control electrode of the SCR 34 and its collector is connected by means of a resistor 36 to the junction 5931 of the resistors 37 and 39. The cathode of the zener diode 43 is connected to the junction of resistors 37 and 39 and its anode is connected to the other terminal of the capacitor 32. An integrating capacitor 42 is connected between the connection point of the resistors 39 and 40 and the capacitor 42.

A voltage distribution circuit comprising resistors 44 and 45 connected in series and a potentiometer 46 is connected across a capacitor 32. The anode of the zener diode 47 is connected to the junction of the resistors 44 and 45 and its cathode is connected to the base of the transistor 35.

At the beginning of the line gap, the amplitude of the deflection current of the deflection coil 17 is at its maximum negative value and decreases linearly as the current passes through the diode 16 and the coil 17 charging the capacitor 18. Approximately in the middle of the line spacing, the deflection current becomes zero and changes; the attenuation diode 16 and now conduct and the SCR 15, which has received a positive control pulse from the waveform circuit 26 during the first half of the line, now conducts a path to ground through the coil 17 for the energy stored in the capacitor 18, which also acts as a 5-correction capacitor. It should be noted that the average voltage across the capacitor 18 is of the order of 50 volts and the capacitor is large enough to charge and discharge only partially in the vicinity of the nominal 50 volt average charge during each deflection period.

During the duration of the line, the commutating switch 11 is open and the capacitors 23 and 24 are charged in parallel through the commutating coil 22 by the energy stored in the winding 27a of the input choke 27. Shortly before the end of the line interval, the positive control of the horizontal oscillator 25 turns on the SCR 12 and begins to conduct starting a commutation interval. Currently, the first and second resonant circuits are formed; the first is formed by the SCR 12, the coil 22 and the capacitor 24 and the second is the SCR 12, the coil 22, the capacitor 23 and the SCR 15, which now conduct current in two directions.

The resonant current through the SCR 15 from the capacitor 23 increases faster than the increasing deflection current, and when the former exceeds the latter, the SCR 15 becomes non-conductive. Currently, current is applied to diode 16, but as the resonant current from capacitor 23 changes its signal, diode 16 switches to the inhibit position, interrupting the deflection current, terminating the line spacing and starting the reset period. During the recovery period, which is entirely within the commutation interval, energy is supplied through switch 11, coil 22 and capacitors 23 and 24 through deflection coil 17 to regenerate capacitor 18 charge and through switch 11, coil 22 and capacitors 23 and 24 to regenerate energy in the primary winding 19 .

During the energy exchange recovery time, the SCR 12 and the diode 13 are rendered non-conductive by the resonant voltage in turn reversing the biases of both devices, opening the switch 11.

The commutation interval ends slightly after the start of the line interval, when the currents in the capacitors 23 and 24 approach zero and the diode 13, which has conducted for the second time during the commutation interval, does not conduct. During the commutation interval, when the switch 11 is closed, the coil 27a is connected between the supply voltage source and ground and thus conducts a linearly increasing current. At the end of the commutation period, when the switch 11 opens, the energy stored in the winding 27a again charges the capacitors 23 and 24 to prepare for the next commutation period.

From the above description of the deflection circuit operation, it is to be understood that any change in DC operating voltage connected through the coil 27a to the circuit switching portion changes the amount of energy stored in the primary winding 19a and capacitor 18 and thus causes undesirable changes in acceleration voltage and image width.

Fig. 2 is a schematic representation of the correspondence between the mains AC voltage (abscissa) and the DC operating voltage (coordinate) due to the effect of the power supply and the control part of the deflection system according to Fig. 1. Curve 48 shows the DC output voltage of the rectifier 28 and the filter circuit 29 as a function of the mains voltage. As the mains voltage changes from 105 volts to 135 volts, the DC voltage changes from about 130 volts to 170 volts. Since such mains voltage fluctuations around the nominal value of 120 volts can occur frequently, it is obvious that some kind of control method is necessary. In addition, it is desirable to operate the deflection circuit at a constant DC voltage of about 170 volts, as shown by curve 49 in Figure 2, which 5931 6 is above the curve obtained from the rectified mains voltage except at very high mains voltages. The control part of the deflection system according to Fig. 1 has the function of raising the rectified mains voltage and adjusting it to maintain this raised value when the mains voltage varies. To achieve this, the booster control circuit adds a voltage to the rectified mains voltage corresponding to the difference between curves 48 and 49.

Figures 3A-3G show normalized voltages and current waveforms obtained at various points in the circuit of Figure 1 and are referred to thereafter in the discussion of the circuit control section. The time axis and relative amplitudes of the waveforms are not plotted to facilitate plotting. The parts of the circuit 1 according to Fig. 1 from which the waveforms of Figs. 3A to 3G have been obtained are marked with the letters A-G in the circuit.

When the circuit starts operating when the television receiver is turned on, the rectified mains voltage is connected through the diode 30 and the current limiting resistor 31 to the input choke winding 27a to start the operation of the deflection circuit, as described above. When the deflection circuit operates, the voltage according to the waveform 50 of Fig. 3A is generated over the commutating switch 11. The commutation interval is represented by the 0-volt portion of the waveform 50. Here, the waveform is coupled to the winding 27b of the input choke 27 and inverted waveforms 51 appear in Fig. 3B to ground at the junction of the winding 27b, capacitor 38 and inductance 33. In the implementation according to Figure 1, the positive part of the waveform 51, i.e. the commutative period, is rectified by means of the SCR 34 to be added to the rectified mains voltage across the capacitor 32. In this arrangement, energy is taken from the deflection circuit only during commutation and thus its effect on the operation of the deflection circuit is very small during the line spacing.

The waveform 51 is also connected by a capacitor 38 and a resistor 37 to the cathode of the zener diode 43 with the anode connected to the Vo source. The zener diode 43 is selected to intersect the positive portion of the waveform 51 so that the same peak voltage always occurs above it regardless of the positive peak level variations of the wave 51. The solid cut waveform over the zener diode 43 is represented by the voltage wave 52 of Figure 3C. The waveform 52 is coupled by a resistor 36 to supply a collector operating voltage to the control transistor 35. The wave 52 is integrated by a resistor 39 and a capacitor 42 to form a constant amplitude saw blade voltage 40. to form the base bias of transistor 35.

The voltage divider formed by the series resistors 44, 45 and the potentiometer 46 knows all changes in the VQ supply voltage. The zener diode 47 connected between the base of the transistor 35 and the connection point of the resistors 44 and 45 forms a path of variable conductivity, changing the base current supplied to the transistor 35 and thus the time during which the SCR 34 conducts during each deflection period.

In the case where the mains voltage is low, the VQ DC voltage also tends to decrease to a lower positive level. This causes a smaller voltage drop in the resistor 44. With a smaller positive voltage at the anode of the zener diode 46, the voltage at its cathode may increase by a corresponding amount before the zener diode 43 conducts. Thus, the saw blade voltage from the capacitor 42 supplies only the base circuit of the transistor 35 and all current from the capacitor 42 controls the base of the current amplifier 35. The voltage at the emitter of transistor 35 then in turn turns SCR 34 on at time TQ (commutation - start of the time interval, as indicated by the timing lines common to all Figures 3A-3G) and allows SCR 34 to conduct at time 1'2, which occurs slightly after the end of the commutation interval. In this way, the maximum amount of energy is charged in the charge capacitor 32, and the voltage V - e, j 0 then increases. The saw blade voltage waveform applied to the base of transistor 35 when the mains voltage is low is shown in Figure 3D as waveform 53. The current waveform in the main pass path of SCR 34 under these conditions is shown in waveform 55 of Figure 3F.

Correspondingly, when the mains voltage is high, the V voltage tends to increase more positively, and an increased voltage drop occurs in the voltage divider and the resistor 44. This raises the voltage at the cathode and anode of the zener diode 47. The zener diode 47 then begins to conduct at a previous point on the time axis of the saw blade voltage across the capacitor 42 and thus forms a bypass for resistor 45 from capacitor 42 and potentiometer 46 The saw blade voltage must then increase to a more positive 8,59316 level before the transistor and thus the SCR 34 conduct.

This shortens the time within the commutation interval when energy is added to the capacitor 32 and thus lowers the V voltage.

Resistor 45 and potentiometer 46 are in the discharge path of capacitor 42 under the conduction of zener diode 47 and thus determine the amount of saw blade bias voltage removed from transistor 35. Potentiometer 46 is adjusted according to the voltage at which the adjustment begins.

In a situation where the mains voltage is very high and the SCR 34 does not conduct at all, the operating current of the deflection system is conducted through the diode 30. In this situation, the current limiting resistor 31 prevents a large voltage rise when power is applied from the SCR 34 to the diode 30.

The inductance 33 in series with the SCR 34 is selected to control the rate of current rise and thus turn off the SCR 34 at the end of the commutation interval. The magnitude of the inductance 33 can be selected to control the maximum amount of energy passing through the SCR 34 and stored in the capacitor 32. The energy transferred from the inductance 33 and the choke leakage inductor to the capacitor 32 can be seen as a positive deviation of waveform 50 in Figure 3A.

Since the voltage V is regulated when it is supplied to the input choke 27, auxiliary power supply circuits connected to the auxiliary chokes of the choke or the windings of the horizontal output transformer 19, such as a rectifier circuit for generating a supply voltage to the video circuits of the television receiver or Figure 4 is a schematic diagram of another implementation of an additional voltage B + controller for a deflection system in accordance with the invention. Those circuit elements according to Fig. 4 which perform similar functions as the correspondingly numbered elements in Fig. 1 are provided with the same reference numerals as in Fig. 1. For convenience, the actual deflection circuit is omitted from Fig. 4. However, it should be understood that the deflection circuit of Fig. 1 can be used in Fig. 4. The auxiliary voltage B + controller circuit of Figure 1 used the SCR 34 as a half-wave rectifier for the AC current from the input choke 27. In addition to the control function, the circuit according to Fig. 1 was formed with an additional voltage B so that the operating voltage supplied to the deflection circuit was of the order of 170 volts. In the implementation of 5931 6 according to Fig. 4, full-wave rectification is used to generate an even more strongly regulated voltage, the operating voltage using the additional voltage being of the order of 200 volts. In general, with the exception of the full-wave rectifier section, the operation of the control circuit is similar to that of the embodiment of Figure 1.

In Fig. 4, the AC mains voltage is rectified by a rectifier diode 28 and filtered in a filter circuit 29. When the receiver starts operating and operates at a very high mains voltage, the supply voltage for the deflection circuit is applied to

When the mains voltage is low, the operating voltage V 1 tends to decrease. During each deflection cycle commutation interval, the positive portion of the waveform 51 is coupled through the coil 19c of the horizontal output transformer of Fig. 1 to the inductance 33 and rectified by the SCR 34. The current flowing through the SCR 34 charges the capacitor 32. This generates a higher voltage across the storage capacitor 32 and is connected through the coil 27a to supply the deflection circuit.

As in the arrangement of Figure 1, in the case of a low mains voltage, less voltage is present across the voltage distribution circuit formed by the resistors 44, 45 and the potentiometer 46, and thus a lower voltage is generated across the resistor 44. This lowers the positive voltage at the anode of the zener diode and thus allows the base voltage of the transistor 35 to increase before the zener diode 47 conducts. This allows the transistor 35 to conduct the entire commutation interval with the integrated saw blade voltage connected to the base of the transistor 35. Thus, the transistor 35 turns on the SCR 34 at the beginning of the commutation interval and the SCR 34 passes current to charge the capacitor 32 throughout the commutation interval and shortly after the time T2, thus providing the maximum voltage gain to the rectified mains voltage.

In this implementation, the coil 19c of the horizontal output transformer in Fig. 1 is connected in series with the coil 27b of the input choke. Although the circuit operates without the addition of winding 19c, the addition of this winding forms a reset pulse which occurs during the commutation time interval and the energy of which is simply added to the energy of the commutation pulse passing through the SCR 34. This arrangement increases the energy stored in the capacitor 32 during the commutation interval.

The diode 60, the cathode of which is connected to the capacitor 61 and the inductance 33 and the anode of which is connected to the winding 27b, is connected in the opposite direction to the SCR 34 and rectifies during the line spacing of the waveform 51 to be added to the added voltage V '. During the line interval, when the line portion of the waveform 51 is negative, current passes through the diode 60 and is stored in the capacitor 6. This arrangement corresponds to the operation of the voltage doubler circuit, discharging the capacitor 61 during the next commutation interval. This charge is increased both in the case of high mains voltage and in the case of low mains voltage as long as the SCR 34 conducts.

In the case of a high mains voltage, the voltage drop across the voltage divider and thus the resistor 44 is larger, creating a higher positive voltage at the anode of the zener diode 47. In this case, in the implementation according to Fig. 1, the zener diode 47 previously conducts a saw blade with a rising part of the voltage, which voltage is applied to the base of the transistor 35. When conducted by the zener diode 47, it short-circuits the main current from the transistor 35, which thus conducts only at a later point in the saw blade voltage rise. Thus, the SCR 34 conducts only a short time, if any, during the commutation interval and less current passes through it to charge the capacitor 32, thus tending to reduce the output voltage V '. As mentioned above, the diode 60 still conducts during the line portion of the waveform 51 as the voltage is adjusted by the SCR 34 and the associated control circuit.

In Fig. 4, the circuit 65 senses the waveform 50 of the changeover switch 11 of Fig. 3A to add an electron beam current control function to the circuit. The wave 50 obtained from the anode of the SCR 12 of the switch 11 in Figure 1 is rectified by a diode 62, filtered by a capacitor 63 and connected via a resistor 64 to the junction of the resistors 44 and 45 of the voltage divider. The higher electron beam current is generated by the lower peak voltage of wave 50 and thus lowers the voltage 5931 6 at the junction of resistors 44 and 45, which causes compensation of the control circuit and raises the booster voltage, as described above. Since the voltages measuring the variations of the mains voltage and the voltages measuring the changes in the electron beam current are opposite to each other, the values of the resistors 44 and 64 are selected according to this type of control. The electron beam current control circuit can be used as well with the half-wave circuit shown in connection with Fig. 1.

Claims (3)

12 5931 6 Claims: A control circuit for a horizontal deflection generator having a direct current source (28, 29), a sensing circuit (35-1 + 7) connected to a voltage source (Vo) representing the energy level in the deflection generator to provide a control signal, an inductance connected to the horizontal deflection generator as well as an adjustable switch (3 * 0 connected in series with a DC power supply (29) and an inductance (275 33) to supply operating current to the horizontal deflection generator, characterized in that the inductance (27, 33) supplies voltage to the adjustable switch to change this to a non-conducting state when the current in the inductance decreases to zero as a result of a change in the polarity of the alternating current voltage during each horizontal deflection period, the adjustable switch control electrode connected to said control circuit (35 ~ 1 + 0, 1 + 2, 1 + 3 »1 + 7) during the adjustment period to adjust the energy level in the horizontal deflection generator. A circuit according to claim 1, characterized in that said inductance has a first winding (27a) connected to said deflection generator and a second winding (27b) connected to an adjustable switch (31 +), said second winding being magnetically connected to said first winding. a coil. A circuit according to claim 1 or 2, characterized in that the inductance has a return coil (33) connected to said deflection generator.