Remote responsive television receiver ferroresonant power supply

In a television receiver with a regulated power supply that is responsive to the state of a remote on/off command signal, a power oscillator is coupled to an unregulated direct voltage source for developing an alternating input voltage of a frequency determined by the frequency of operation of the oscillator. The oscillator is provided with a frequency control terminal that controls the oscillator frequency, depending upon a control signal applied to the terminal. A ferroresonant or self-regulating circuit is energized by the alternating input voltage to produce a regulated supply voltage that in turn energizes a load circuit within the television receiver. A remote control circuit responsive to the on/off command signal applies a control signal to the frequency control terminal of the oscillator such that during the on-state of the command signal the oscillator operates at a frequency that permits normal, ferroresonant operation of the self-regulating circuit and that during the off-state of the command signal, changes the oscillator frequency to a different one that is high enough to disable the ferroresonant operation of the self-regulating circuit. The power supply is thereby placed in the standby condition wherein the television display load circuit is substantially deenergized.

This invention relates to a remote responsive ferroresonant power supply 
for a television display system. 
A ferroresonant power supply may be used to provide a regulated ultor 
voltage and a regulated B+ scanning voltage for a television receiver. 
When operated at a relatively high input frequency, such as the horizontal 
deflection frequency of about 16 KHz, a ferroresonant power supply is a 
relatively compact and low weight unit that provides inherent output 
voltage regulation without the need for relatively complex and expensive 
electronic regulator control circuitry. 
Many television receivers include remote control circuitry that provides 
remote on/off power control. In remote controlled switching power supplies 
for television receivers, the remote control circuitry may disable the 
switching element or otherwise alter switching to place the television 
receiver in the standby mode of operation. 
A feature of the invention is a ferroresonant power supply for a television 
receiver that incorporates remote on/off power control. A power oscillator 
is coupled to a source of first voltage for developing an alternating 
input voltage of a frequency determined by the frequency of operation of 
the oscillator. The oscillator includes a frequency control terminal that 
controls the frequency of operation of the oscillator depending upon a 
control signal applied to that terminal. A self-regulating or 
ferroresonant circuit is energized by the alternating input voltage for 
producing a regulated supply voltage that in turn energizes a load circuit 
within the television display system. A remote control circuit is 
responsive to a remote on/off command signal for applying to the 
oscillator frequency control terminal a control signal such that during 
the on-state of the command signal the oscillator operates at a frequency 
that permits normal ferroresonant operation of the self-regulating 
circuit, and that during the off-state of the command signal, the 
oscillator operates at a different frequency that disables ferroresonant 
operation to thereby substantially deenergize the television display 
system load circuit.

In FIGS. 1a and 1b, a ferroresonant power supply 10 for a television 
receiver or television display system comprises a source 80 of unregulated 
direct voltage Vin and a power oscillator 7 energized thereby. Power 
oscillator 7 comprises a high leakage inductance transformer 22 having a 
primary winding comprising sections 22a and 22b coupled in a push-pull 
arrangement to output switching transistors Q1 and Q2 of an inverter 20. 
The DC voltage source 80 comprises a source 81 of alternating polarity 
mains supply voltage coupled across input terminals 91 and 92 of a 
full-wave bridge rectifier 84 to develop the direct voltage Vin across a 
filter capacitor 86 coupled between a terminal 23 and a ground 24 not 
isolated from mains supply source. Nonisolated ground 24 is coupled to the 
current return terminal 93 of bridge rectifier 84. One end of mains supply 
voltage source 81 is coupled to terminal 91 through a fuse 82 and a 
current limiting resistor 83. The other end of source 81 is coupled to 
terminal 92 through a switch 85 that is normally in the closed position in 
both standby and full power modes of operation. Thus, the input voltage 
Vin is available for use in both modes of operation. 
Alternate conduction in the collector-to-emitter main current paths of the 
transistors Q1 and Q2 develops a rectangular or square-wave alternating 
polarity input voltage across each of the primary winding sections 22a and 
22b of power transformer 22. The alternating polarity square-wave voltage 
developed across each of the primary winding sections produces an 
alternating polarity supply voltage of the same frequency across each of 
secondary windings 22c-22f of power transformer 22. Secondary windings 
22c-22e have a common center tap coupled to a chassis ground 26 that is 
isolated from ground 24. 
The alternating polarity output voltage developed across winding 22c is 
full-wave rectified by diodes 72 and 73 and filtered by a capacitor 74 to 
develop a DC supply voltage, of illustratively +230 volts, to power such 
circuits as the television receiver picture tube driver circuits. The 
alternating polarity output voltage developed across winding 22e is 
full-wave rectified by diodes 64 and 65 and filtered by a capacitor 61 to 
develop a DC supply voltage, of illustratively +25 volts, to power such 
television receiver circuits as the vertical deflection circuit, the audio 
circuit, and the chroma-luma circuits. 
The alternating polarity output voltage developed across winding 22d is 
full-wave rectified by diodes 62 and 63 and filtered by a capacitor 39 to 
develop, at a B+ terminal, a B+ scan supply voltage to energize a 
horizontal deflection generator circuit 30 for developing horizontal 
scanning current in a horizontal deflection winding 31. Horizontal 
deflection circuit 30 is coupled to the B+ terminal through an inductor 38 
and comprises a horizontal oscillator and driver 34, a horizontal output 
transistor 35, a damper diode 36, a retrace capacitor 37, and the series 
arrangement of horizontal deflection winding 31, an S-shaping or trace 
capacitor 32, and a winding 33a of a saturable pulse transformer 33. 
Saturable pulse transformer 33 provides pulses that establish the 
frequency of operation of inverter 20 at the horizontal deflection 
frequency in synchronism with the horizontal deflection or scanning 
current, as will be later described. 
The alternating polarity output voltage developed across a high voltage 
winding, secondary output winding 22f, is coupled to a high voltage 
circuit 21 to develop a DC ultor voltage or accelerating potential at a 
terminal U for the television receiver picture tube, not illustrated. High 
voltage circuit 21 may comprise a conventional voltage multiplier circuit 
of the Cockroft-Walton type, or may comprise a half-wave rectifier 
arrangement with a polarity of winding sections of winding 22f, the 
sections not being individually illustrated. 
The output voltage Vout developed across secondary output winding 22c, 
between terminals 28 and 29, is regulated by the ferroresonant operation 
of a ferroresonant load circuit 25, as described in the U.S. patent 
application Ser. No. 220,847, filed Dec. 29, 1980, by D. H. Willis, 
entitled "TELEVISION RECEIVER FERRORESONANT LOAD POWER SUPPLY", and in 
U.S. patent application Ser. No. 255,396, filed Apr. 20, 1981, by D. H. 
Willis, entitled "TELEVISION RECEIVER FERRORESONANT LOAD POWER SUPPLY WITH 
REDUCED SATURABLE REACTOR CIRCULATING CURRENT", both applications herein 
incorporated by reference. Ferroresonant load circuit 25 comprises a 
saturable reactor 27 including a magnetizable core 127 and a winding 27a 
located thereon, a capacitor 88 coupled between terminals 28 and 29 and a 
winding 22g of transformer 22 magnetically tightly coupled to winding 22a 
and conductively coupled in series with saturable reactor winding 27a 
across capacitor 88. 
By being coupled to transformer secondary output winding 22c, ferroresonant 
load circuit 25 acts as a regulating load circuit to maintain the voltage 
across winding 22c as the regulated voltage Vout. With the voltage across 
secondary output winding 22c regulated by the ferroresonant operation of 
ferroresonant load circuit 25, the output voltages across all the other 
secondary windings that are tightly coupled to winding 22c, including high 
voltage winding 22f, are also regulated. Because of the loose magnetic 
coupling between each of the primary winding sections 22a and 22b, and 
each of the secondary windings 22c-22f, the voltage across the secondary 
windings can remain relatively unchanged in amplitude or half-cycle area, 
even though the voltages across the primary winding sections vary in 
amplitude. 
Transformer 22, in combination with capacitor 88, develops an exciting 
current in saturable reactor winding 27a for generating a combined 
magnetic flux in core 127 that links winding 27a to produce the 
alternating polarity output voltage Vout. To regulate Vout by 
ferroresonant operation, capacitor 88 generates a circulating current 
during each half cycle of the alternating polarity output voltage that 
aids in magnetically saturating the core section of magnetizable core 127 
that is associated with the reactor winding. 
As the saturable core section goes into saturation and comes out of 
saturation, the inductance exhibited by saturable reactor winding 27a 
switches between a low inductance and a high inductance. This switching 
action is a function of the saturation characteristics of the magnetizable 
material of core 127. The amplitude of the output voltage, the half-cycle 
area of the output voltage, or both the amplitude and half-cycle area are 
regulated by this switching action against changes in the amplitude of the 
DC input voltage developed across terminals 23 and 24 and against changes 
in the loading on the various DC supply terminals including the ultor 
supply terminal U. 
Inverter 20, in addition to switching transistors Q1 and Q2, includes 
damper diodes 44 and 45, each paralleling a respective base-emitter 
current path of the switching transistors, and a feedback winding 22i of 
transformer 22 tightly coupled magnetically to primary winding sections 
22a and 22b and conductively coupled to the bases of transistors Q1 and 
Q2, respectively. The emitter electrodes of switching transistors Q1 and 
Q2 are coupled to a frequency control terminal 9 of controllable 
oscillator 7 through respective resistors 68 and 71. Frequency control 
terminal 9 is coupled to nonisolated ground 24 by an impedance, resistor 
13, that is paralleled by the mechanical on/off switch portion 14 of a 
relay 99. Relay 99 is energized by the current in relay coil 15 to actuate 
the mechanical switch 14 into the closed position to make contact with the 
ON terminal of the switch. 
Relay 99 is part of a remote control circuit 90 for the remote responsive 
ferroresonant power supply 10. To turn the television receiver on, or to 
switch it from standby condition to full power condition, the on-state of 
a remote on/off command signal is received by a remote signal processor 96 
along an input signal line 95. Upon receipt of the on-state of the command 
signal, the output signal line 17 of remote signal processor 96 goes low 
to turn on a transistor 16 having a base electrode coupled to signal line 
17 through a resistor 97. A resistor 98 is coupled between the base and 
emitter electrodes of transistor 16. The collector electrode of transistor 
16 is coupled to relay coil 15 and the emitter electrode is coupled to a 
terminal 94. At terminal 94, there is developed a +12 volt supply voltage 
that is available during both the on and off states of the remote command 
signal. 
With transistor 16 conducting during the on-state of the command signal, 
current flows in relay coil 15 to energize relay 99 and actuate mechanical 
switch 14 to move it from the STANDBY terminal and make contact with the 
ON terminal. When mechanical switch 14 closes, the impedance from 
frequency control terminal 9 to earth ground 24 changes from that of 
resistor 13 to that of a short-circuit impedance. The control voltage 
v.sub.fr being developed at terminal 9 is now substantially zero relative 
to ground 24. 
When terminal 9 becomes short circuited to ground, operation of oscillator 
7 switches from the standby-mode of operation to the on-mode of operation. 
During a start-up interval, after oscillator 7 switches to the on-mode of 
operation, but prior to synchronized operation, positive feedback provided 
by winding 22i of transformer 22 produces a free-running operation at a 
frequency between 5 and 10 KHz, a frequency lower than the horizontal 
deflection frequency, as described in the U.S. patent application of D. W. 
Luz et al., Ser. No. 174,943, filed Aug. 4, 1980, entitled "TELEVISION 
RECEIVER, PUSH-PULL INVERTER, FERRORESONANT TRANSFORMER POWER SUPPLY 
SYNCHRONIZED WITH HORIZONTAL DEFLECTION", herein incorporated by 
reference. A start-up resistor 58 is coupled between terminal 23 and the 
base of switching transistor Q1 to initiate switching action when switch 
85 is initially closed. 
In the start-up mode of operation, with oscillator 7 operating at 5 to 10 
KHz frequency, output voltages are developed at the various DC supply 
voltage terminals coupled to the secondary windings 22c-22f of power 
transformer 22. Horizontal deflection generator 30 is sufficiently 
energized to begin developing scanning current i.sub.y in deflection 
winding 31 and to begin developing a synchronizing control pulse across 
winding 33a of pulse transformer 33. 
The synchronizing pulse developed across winding 33a is transformer coupled 
by way of secondary windings 33b and 33c to inverter 20 to increase the 
frequency of operation to the horizontal deflection frequency and to 
synchronize operation with horizontal scanning current generation. 
Operation at the horizontal deflection frequency produces an increase in 
the output voltages across the secondary windings 22b-22f of transformer 
22 to their normal, steady-state values. 
The control circuit of oscillator 7 includes turnoff control transistors 42 
and 43 coupled respectively to the bases of switching transistors Q1 and 
Q2, and saturable pulse transformer 33 having secondary windings 33b and 
33c coupled respectively to the bases of turnoff control transistors 42 
and 43 through respective resistors 48 and 49. 
As described in the aforementioned Luz et al. U.S. patent application, the 
horizontal deflection current i.sub.y flowing through the primary winding 
33a of pulse transformer 33 maintains the core 133 in magnetic saturation 
during each deflection cycle, except during those intervals near the two 
zero-crossover instants of the deflection current when the core comes out 
of saturation to produce output pulse voltages across secondary windings 
33b and 33c. Near the zero-crossover instant within the trace interval, a 
positive voltage pulse is produced at the dotted terminal of winding 33b 
and is applied to control transistor 42 to turn the transistor on, thereby 
turning off switching transistor Q1. Near the zero-crossover instant 
during the retrace interval, a positive pulse is produced at the undotted 
terminal of winding 33c and is applied to control transistor 43 to turn 
the transistor on, thereby turning off switching transistor Q2. A diode 18 
is coupled in series with a small inductor, such as ferrite bead, FB, 
across pulse transformer winding 33a for the purpose of keeping the core 
133 magnetically unsaturated longer within the retrace interval. The pulse 
voltage during retrace produced across winding 33a is therefore broadened 
sufficient to turn on transistor 43 for the proper duration. 
As described in the U.S. patent application of D. W. Luz, Ser. No. 288,237, 
filed July 29, 1981, entitled "DUTY-CYCLE CONTROLLED INVERTER POWER SUPPLY 
FOR A TELEVISION RECEIVER", herein incorporated by reference, a feedback 
voltage, representative of the current flowing in the collector path of 
switching transistor Q1 is developed across resistor 68. The feedback 
voltage developed across resistor 68 is applied to pulse transformer 
secondary winding 33b by way of a resistor 67 and after filtering by a 
capacitor 66, to provide voltage biasing of the base of turnoff transistor 
42, to obtain a substantially 50% duty cycle switching of transistor Q1 
under varying collector current levels. A similar feedback voltage to 
control the duty cycle switching of transistor Q2 is developed across 
resistor 71 and applied to pulse transformer secondary winding 33c by way 
of a resistor 70 after filtering by a capacitor 69. 
An auxiliary voltage supply 19 of FIG. 1b develops the +12 volt supply 
voltage at terminal 94 for energizing remote control circuit 90 of FIG. 
1a. In supply 19, an auxiliary winding 22h, magnetically tightly coupled 
to primary winding sections 22a and 22b of transformer 22, produces a 
square-wave voltage at the horizontal deflection frequency during 
steady-state operation of ferroresonant power supply 10. This voltage is 
rectified by a diode 87 and filtered by a capacitor 89 to produce the 12 
volts DC at terminal 94. 
To turn the television receiver off or into the standby mode of operation, 
the off-state of the remote command signal is received by remote signal 
processor 96 along input signal line 95 to produce a high signal level on 
output line 17. Transistor 16 becomes cut off, deenergizing relay 15, 
opening mechanical on/off switch 14 to disconnect the ON terminal of relay 
99 from ground 24. 
In the standby-mode of operation with mechanical on/off switch 14 
disconnected from frequency control terminal 9, the current flowing in the 
main collector-to-emitter paths of switching transistors Q1 and Q2 flows 
from terminal 9 through resistor 13 to earth ground. During each half 
cycle of inverter operation, a ramp of current flows in resistor 13, 
producing a ramp, frequency control voltage v.sub.fr at terminal 9. The 
ram voltage v.sub.fr is coupled through respective capacitors 66 and 69 
and pulse transformer secondary windings 33b and 33c to the base resistors 
48 and 49 of turnoff control transistors 42 and 43. 
During each half cycle of inverter operation, the ramp current flowing in 
transformer primary winding section 22a or 22b increases to a point where 
the ramp voltage v.sub.fr forward biases the appropriate turnoff control 
transistor 42 or 43 to shunt base current away from whichever one of the 
switching transistors Q1 and Q2 is conducting. That switching transistor 
then becomes cut off, to initiate the next half cycle of inverter 
operation. 
By appropriate choice of the resistance value of resistor 13, a ramp 
voltage v.sub.fr is developed that produces inverter operation in the 
standby condition at a frequency substantially higher, 3 or more times, 
than the horizontal deflection frequency of the steady-state inverter 
operation. At the higher frequency of operation of the inverter 20 and of 
the power oscillator 7, at for example, 100 KHz, ferroresonant operation 
of ferroresonant load circuit 25 cannot be sustained due to the inability 
of the core 127 of saturable reactor 27 to reach the point of magnetic 
saturation within the shortened half cycle interval available during the 
higher frequency operation. 
With ferroresonant operation of self-regulating load circuit 25 being 
disabled by the standby-mode, higher frequency, inverter operation, the 
output voltages being developed across secondary windings 22b-22f of power 
transformer 22 are reduced to a point where most if not all of the 
television receiver load circuits coupled to those windings are 
substantially deenergized. 
Auxiliary power supply 19, however, still provides the +12 volts needed by 
remote control circuit 90 for operation in the standby-mode. Since 
auxiliary winding 22h is tightly coupled to primary winding sections 22a 
and 22b of transformer 22, the amplitude of the higher frequency 
square-wave voltage does not differ significantly from the on-mode 
amplitude. The voltage being developed at terminal 94 is therefore 12 
volts even during standby operation.