JPH03113968A - Television display - Google Patents

Abstract

PURPOSE: To reduce power consumption during wait by keeping a horizontal output transistor TR continuously saturated while waiting and short-circuiting a horizontal sweep switch to start the waiting operation. CONSTITUTION: During wait, a TR Q4 is in a saturated forward conduction state or the reverse collector conduction state, in which even a damper diode D7 is made conductive. Currents i'1 and i1 , flowing into the collector of the horizontal output TR Q4 according to a winding mode W2 in the wait mode have the same shape and amplitude approximately. Since currents i1 and i'1 are practically smaller than those during operation in the normal mode during operation in the wait mode, the power consumption of an SICOS-type power source 20 during wait is relatively small and is, for example, 6 watts. At the time of returning a television receiver to the normal operation, a turning-on command signal of a positive pulse is applied from a remote control circuit 30 to the base of a switching TR Q2 through a line 31 for control for about one second, and a holding current of the TR is sufficiently obtained from a line 26 for holding thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention relates] The present invention relates to standby operation of a television receiver, and particularly to supplying power to a remote control circuit within the television receiver during standby operation. Regarding power supply. This invention is a return drive type main power supply,
In particular, it can be used in a power supply of a single conversion method (5ICOS type, that is, a method of converting unregulated AC voltage into a regulated AC voltage and supplying it as the power supply voltage) as described in British Published Patent Specification No. 2094085A. I can do it.

[Prior art]

Several types of standby circuits for television receivers are known, such as a small AC line voltage transformer that supplies power to the television receiver's remote control circuit and a circuit that turns the television receiver on and off.
There is a relay that switches off. Although some standby circuits of this type consume only about 6 watts, they are relatively expensive as standby power supplies.

Another type of standby circuit is a switched mode power supply with an integrated circuit controller, such as the TDA 4600, and a relay that interrupts most of the secondary voltage during standby. This switchable mode power supply has approximately
Operates at 0 KHz, but standby power consumption is 10-2
It is relatively large at 0 watts.

Yet another type of standby circuit is a mains transformer coupled to a switched mode regulator without a relay.

During standby, the horizontal oscillator is deenergized by the remote control circuit, but
Using mains transformers is a relatively cumbersome method of designing standby circuits.

[Disclosure of the invention]

A feature of the standby circuit of the present invention is that standby operation is initiated by shorting the horizontal sweep switch, for example by keeping the horizontal output transistor in continuous saturation during standby. When using a mains power supply such as the 5ICOS type power supply described above, a short circuit in the sweep switch causes the power supply to free-run oscillate around the horizontal deflection frequency with a shock coefficient approximately equal to the ratio of the sweep (trace) period to the retrace period (retrace). The power for the standby remote control circuit that generates the power flows from the flyback transformer through the shorted sweep switch, and this standby power consumption is typically about 6 watts under 10 watts, and the power used for the remote control circuit is The possible electrical power is about 1.5 watts at 12 ports.

[Embodiments of the invention]

In FIG. 1, 5I described in the above-mentioned British published patent specification
A CO9 type power supply 20 is connected to the secondary winding group of a flyback transformer 1, which includes a high voltage winding W4 to which a high voltage anode load 33 is coupled from an unregulated B1 power supply terminal of a television receiver. It functions to supply power to various load circuits. During normal mode operation, the horizontal retrace pulse voltage v3 of FIG. 2C generated by the horizontal deflection generator 21 is transformer coupled from the secondary winding w2 of the flyback transformer T1 to the primary winding lllll. .

The positive retrace pulse from the tap of primary winding Wl is peak rectified by diode D1, filtered by capacitor C1, and applied to S IC0S regulator control circuit 22 via signal line 34. The regulator control circuit 22 is synchronized with the horizontal deflection by a retrace pulse voltage applied via a signal line 29 and produces a pulse width modulated signal 23 whose duty factor varies with changes in the amplitude of the retrace pulse voltage. This pulse width modulation signal 23 is applied to the input terminal 24 of the 5ICOS type electric terminal 20 to pulse-modulate the push-pull switches Sl and S2. This switch includes a transistor Tri or Tr2 each having an anti-parallel diode (not shown) between the collector and emitter, and pulse width modulates the operation of switches S1 and S2 to adjust the retrace pulse amplitude to the load and B+ voltage conditions. It is designed to remain relatively constant against changes in .

The positive voltage developed across capacitor C1 keeps transistor Ql in saturation, thereby lowering its collector voltage to ground 2.
5 and reverse bias the diode DIO. On the secondary side of the flyback transformer 〒1, the standby switching transistor Darlington transistor Q2 connects to the holding line 2.
The phasing is maintained by the base current flowing from the resistor R9 to the Zener diode D5. Therefore, the horizontal sweep switch 27 and the horizontal drive transistor Q5 are connected to the chassis ground point 28 via the remote control switch Q2 which is conducting.

The waveform aNe in Figure 2 shows the normal mode operation of the 5ICOS type power supply and horizontal deflection circuit in Figure 1, and a is 5rc.
This is the switching voltage v1 at the connection point between the output switches s1 and s2 of the OS type power supply 2o. The dashed waveform in FIG. 2 shows the adjustment range of the power supply, and the solid waveform shows the waveform taken at the normal operating point of the power supply.

FIG. 4 shows a detailed embodiment of the circuit of the 5ICO5 type power supply 2G of FIG. Connect to voltage terminal. This switch S1
The rising edge of the pulse width modulation signal 23 makes the transistor R4 conductive near the time T4, so that the switch S2 becomes conductive.
The transistor Tr2 is cut off.

In order to maintain the current 41 in the main winding Lla of the inductor Ll,
The dot terminal of the winding Lla becomes positive with respect to the non-dot terminal, forward biasing the bias diode DS1 of the switch Sl. Therefore, a gradually decreasing current of the winding Lla flows to the B terminal in FIG.

The positive voltage at the dot terminal of the winding Lla induces a positive voltage at the dot terminal of the control winding Llc, and the base of the transistor ↑r1.
Forward bias the emitter junction. The transistor Tri causes current to flow through the winding Lla when the current 11 in FIG. 2 becomes positive during the sweep period T2 to T6 after time T4.

At the end of the sweep period, at time 〒6, a controllable amount of energy is stored in inductor L1, and much of this stored energy is absorbed by the load coupled to flyback transformer ↑1 during horizontal retrace period T6-T7. transferred to the circuit.

At time T6, winding w1 of flyback transformer TI
The positive retrace pulse voltage generated at the dot terminal of the inductor Ll
is applied to the non-dot terminal of the winding Lla, and makes the non-dot terminals of the winding Lla and the control windings Llb and Llc positive. Transistor Tr3 conducts and cuts off transistor Tri. As a result, the voltage Ki+ becomes negative near the center of the return line, and the switch S2
A positive current flows through the diode DS2. That is, even if the transistor Tri is cut off, the current flowing into the dot terminal of the winding Lla is not immediately cut off, and the current flows through the diode []S2. There is a flyback resonant circuit between the retrace inductor L1 and the retrace resonant circuit consisting of the load circuit coupled to the horizontal deflection winding LH of the capacitor CR1 and the secondary windings 3 and 4 of the flyback transformer TI. A resonant transfer of energy through the buck transformer 11 takes place.

Figure 2d shows the base current i3 of the horizontal output transistor Q4 flowing from the dot terminal of the winding Wb of the horizontal drive transformer 〒2, and Figure 2e shows the current 12 flowing in the winding of the drive transformer T2. Horizontal drive transistor Q5 near time 0 TO
conducts and generates a base current i3 in the opposite direction (direction flowing into the dot terminal of the winding Wb), which cuts off the horizontal output transistor Q4 at time T1. Further, generation of current i2 begins near time To, which charges capacitor CB via diode D2. Therefore, the current during normal mode operation is 12
, i3 are generated by the switching action of the horizontal drive transistor Q5.

To switch the television receiver to standby mode operation, a chassis ground potential is applied as an off command signal from the remote control circuit 30 to the remote control switching transistor Q2 via the control line 31 for about 1 second. transistor Q
2 is cut off, the current in the winding W2 of the flyback transformer TI, which had been flowing through transistors Q4 and Q2, flows through the winding We of the horizontal drive transformer, diode D2, and transistor Q3 to the chassis ground point 2B. be swept away by

That is, when a normal current i'1 flows out of the dot terminal of the winding w2 of the flyback transformer, the return path of this current is through the horizontal output transistor Q4 to the drive transformer T2.
The winding %llc enters the dot terminal, and the diode I
12 to charge capacitor C8 to a positive value. Further, when the normal current i'l flows out from the non-point terminal of the winding W2 of the flyback transformer, its return path is through the diode of the Darlington transistor Q2, the damper diode I]7 of the sweep switch 27, and the horizontal output transistor Q4. passes through a diode formed by the base-collector junction of .

Positive current 12 induces a positive base current i3 of horizontal output transistor Q4 in winding wb of horizontal drive transformer T2.

This current i3 keeps the horizontal output transistor Q4 conductive, so that transformer 2 acts as a bootstrap transformer providing positive feedback from the output of that transistor Q4, keeping it in saturation.

During standby, transistor Q4 is in a saturated forward conduction state or in a reverse collector conduction state in which damper diode D7 is also conductive. That is, during standby 2, transistor Q2 is in a non-conducting state, and when current flows from the dot terminal of winding 2 through transistor Q4 and winding WC, current 12 flowing through the winding 2 flows through transistor Q4 to winding Wb. induces a voltage that maintains it in saturation. Also, when current flows into the dot terminal of winding A2, the -7 current is formed by the diode BD681 connected between the emitter and collector of transistor Q2 from the ground point, the damper diode D7, and the base-collector junction of transistor Q4. The current flows through the diode. These conductive conditions effectively short circuit sweep switch 27, connecting the dot terminal of flyback transformer winding W2 to the dot terminal of drive transformer winding wc. If this short-circuiting of the sweep switch 27 continues, the formation of a retrace resonant circuit is prevented, thereby the retrace pulse voltage decreases, and retrace pulses are no longer generated. As a result, the supply current through diodes D4, D6, the supply voltage V
b and the current passing through the holding line 26 become zero. Therefore, remote control transistor Q2 remains cut off even after the one second off command signal period has elapsed.

The voltage Va on capacitor C4 is the supply voltage of the 12-port supply line which energizes remote control circuit 3o and horizontal oscillator 32. This voltage is generated via diodes D2, D3 from the positive current i'l flowing as current 12 in the winding We of the drive transformer in the standby mode of operation. horizontal oscillator 3
2 operates during standby to facilitate the conduction change of the television receiver, as will be described later. Darlington transistor Q3
acts as a shunt regulator to limit the voltage on capacitor C8.

On the primary side of the flyback transformer TI, the retrace pulse is crushed when standby mode operation begins, so the 5 IC
The OS type power supply 20 starts operating in the free running mode. The collapse of the retrace pulse disables the control circuit 22, cutting off transistor Ql. To cut off this transistor Ql, t/R including resistors R1-R4 and capacitor 4jc2
The CI network can now form an astable multivibrator circuit with the five ICOS switches s1 and s2.

The waveforms of FIG. 3 relate to the circuit of FIG. 1 in the standby mode of operation. As shown by the voltage v1 in FIG. 3a, the left plate of the capacitor C2 becomes positive with respect to the right plate near time t1 when the switch S1 of the 5rcos type power supply 2o is conductive after the time t1. When switch S1 becomes conductive, capacitor C2 begins to discharge through resistors R2 and R3, as shown by the decreasing voltage v2 at the collector of transistor Q1 after time t1 in FIG.

The switch Sl of the 5rcos type power supply 20 remains conductive due to the regeneration action of the control windings Llb and Lie in FIG.
As shown in FIG. 3a, the conduction continues until time t3 when the transistor Tri begins to shut off. Note that the current flowing into the dot terminal of the first winding Lla generates a positive voltage at the dot terminal of the control winding Llc, so the transistor Tri is biased in the forward direction until the transistor Tr3 becomes conductive.
At time t4, transistor Tri is cut off and switch S
2 becomes conductive due to conduction of the diode O92, and the voltage Vl becomes the ground potential.

By time t4, capacitor C2 has charged to a voltage of opposite polarity such that the right plate of the capacitor is positive with respect to the left plate. When the positive right plate of capacitor C2 is fixed to ground voltage by switch S2, the base-collector junction of transistor Ql is forward biased, causing the voltage V2 between time t4 and t6 in Figure 3 to be lower than ground voltage. This period of time t is kept slightly lower.
4. During t6, capacitor C2 discharges from the B terminal through the base-collector junction of transistor Ql and resistor R2, and around time t6, the polarity of the voltage on capacitor C2 reverses, reverse biasing the base-collector junction of transistor Ql. . Capacitor C2 starts charging from the B terminal,
The left plate becomes positively charged relative to the right plate.

By time t7 in Figure 3, capacitor C2 is sufficiently charged to forward bias diode 010 and 5ICO.
The control transistor Tr4 of the S-type power supply 2G is made conductive.

Note that since the current flowing out from the dot terminal of the winding Lla generates a positive voltage at the non-dot terminal of the control winding Llb, the transistor Tr2 is biased in the forward direction until the transistor Tr4 becomes conductive. When the control transistor Tr4 becomes conductive, the output switching transistor Tr2 is cut off. When Tr2 is cut off, diode D of switch 91
SL becomes conductive and the inductor L in Figure 4! A current is drawn from the main winding Lla of , so that the voltage v1 rises to the voltage level B shown in FIG. 3a. Note that the diode Ds1 conducts even if the transistor Tr2 is cut off, the winding Ll
This is because the current flowing out from the point terminal a is not immediately interrupted.

Switch 91. The length of one cycle of free-running oscillation of S2 is, for example, 70 ls, and the length of the horizontal deflection period? This free-running period of 70 seconds, close to the 64 circuit seconds of H, is chosen to be short enough to be inaudible to most people in standby mode.

This free-running period can be adjusted by adjusting the value of the resistor R2 of the astable multivibrator.

Figure 3C shows the winding W of flyback transformer 1 during standby operation.
0 winding showing the current flowing in l111. l112 are tightly coupled to each other and the number of turns is almost equal, so turn it in standby mode! ! 1112 therefore horizontal output transistor Q4
The current i'I flowing through the collector of has approximately the same shape and amplitude as the current i1. Current i1 during standby mode operation
．． Since i'l is substantially smaller than that during normal mode operation, the power consumption of the 5ICO5 type power supply 20 during standby is relatively small, for example 6 watts.

FIG. 3d shows the voltage V4 across the remote control switching transistor Q2 during standby operation, during a period t during which the current in the winding W2 of the flyback transformer element 1 is negative.

~t2, diode BD681 of Darlington transistor Q2 is forward biased to fix voltage v4 to chassis ground potential. During the period t2-t3, the current i11'l
is positive and slopes upward to the right. During this period, the current 12 in winding We of transformer T2 is positive, forward biasing diode D2 and charging capacitor C8 to a voltage of approximately 20 volts.

During this period the voltage v4 is positive and the winding W of the drive transformer T2
C and the voltage generated in capacitor C8.

The switch S2 of the power supply 20 of the type S IC09 conducts around the time t3 and starts the negative slope of the current iI, i''l.After the time t3, the current i'1 flowing in the winding W of the drive transformer T2 becomes In order to reverse the polarity of the voltage developed across its windings &iWc, voltage v4 decreases from time t3 to zero crossing time t5 of current i'1.6 At time t5, current i'1 becomes negative and the diode of Darlington transistor Q2 The BD681 is forward biased to fix the voltage v4 to the chassis ground potential again.

Since sweep switch 27 is shorted during standby mode operation, the voltage developed in winding W2 of the flyback transformer is the same as voltage v4 in FIG. 3d. But the AC zero Porto reference level is different. Therefore, the peak voltage of winding 2 during standby operation is, for example, about 25 volts compared to, for example, 900 volts during normal mode operation, and the peak-to-peak voltage decreases to about 3% of that during normal operation. It is.

Since the conduction of the horizontal drive transistor Q5 is prevented by the reverse bias of the diode D8 or D9, the operation of the horizontal oscillator 32 during standby mode operation is limited to the 5ICO5 type power supply 2.
0's self-propelled operation cannot be prevented.

Standby power for remote control circuit 30 and horizontal oscillator 32 is drawn from winding 1llc of horizontal drive transformer 2 as current i2 charging capacitors C8 and C4 during standby operation. Third
The average value of the positive part of the current 12 shown in figure f is approximately 150 mA
Therefore, the available power of the output of the 12-port regulator is 1
．． It is equivalent to 8 watts. A positive current i3 in winding Wb of transformer T2, shown in FIG. 3e, is induced by current 12. This current i3 has a large amplitude because the number of turns of the winding Wb is only 172 as that of the winding We. For example, the inductance of the winding wb is about 200 JLH, and that of the winding WC is about 800 JLH.

Resistors R7 and R8 serve to smooth the base current i3. When D2 is cut off, some energy is stored in the winding WC through resistor R7, stretching the base current i3, and the horizontal output transistor Q4 remains safely saturated until the current through its collector is zero. be done.

To return the television receiver to normal operation, a positive pulse ON command signal is applied from the remote control circuit 30 to the base of the switching transistor Q2 via the control line 31 for about 1 second, and then from the holding line 26 to the base of the switching transistor Q2. Ensure that the transistor has sufficient holding current. The deflection generator 21 including the sweep switch 27 is again connected directly to the chassis ground point 28 via the switching transistor Q2;
The emitter of horizontal output transistor Q4 is set to ground potential. Therefore, the current i′1 in the winding W2 of the flyback transformer
is shunted from winding we of drive transformer T2 to ground by transistor Q2, resulting in a significant reduction in current 12 such that horizontal output transistor Q4 is no longer able to remain saturated.

The operation of the 5rcos type power supply 20 changes to a series of starting operations similar to those described in the above-mentioned British published patent specification, and this operation is caused by the retrace ringing of the primary winding W of the flyback transformer T1.
The amplitude of the retrace voltage applied to I is controlled until it is high enough to reenergize the 5ICO8 regulator control circuit 22. When the regulator control circuit is reenergized, the output switch S
1 is synchronized with the horizontal retrace, the retrace pulse voltage saturates transistor Q1, causing resistor R1-R
The multivibrator network of C.4 and capacitor C2 is deenergized.

During this transition from standby operation to normal operation, what induces current i3 changes from the current in winding *WC of drive transformer T2 to the current in winding Wa; During this period, the cause of inducing current i3 changes from winding Wa to we. In order to perform this transition safely without damaging the horizontal output transistor Q4, the switching action of that transistor Q4 is not interrupted during the transition and it is not made conductive when there is a significant positive voltage V3 on its collector.

During standby, the horizontal oscillator 32 is operating, but when the voltage v4 is low, it is only connected in circuit to the base of the horizontal drive transistor Q5, and the current 1'l flows in the negative direction from the diode of the Gourington transistor Q2. Therefore, even if a switching signal is applied to the base of the drive transistor Q5 during standby, only a small amount of negative current i3 flows and does not affect the operation of the transistor Q4.

When the current 1''l becomes positive, the voltage v4 rises, the collector current of the transistor Q5 is cut off by the diodes D8 and D9, and the positive current i3 continues to bias the transistor Q4 into saturation.

When the television receiver is switched from standby operation to normal operation, transistor Q2 is saturated and immediately after receiving the 2-on command value signal, voltage Vb is zero, so horizontal output transistor Q4
The current i3 driving the is zero. Therefore, the 5tcos power supply circuit 20 continues to run free like during standby, and the return circuit LH, OR
generates a gradually increasing amplitude voltage V3 at the midline frequency during the period t1 to t3 in FIG. 3 through ringing.

Although the automatic frequency phase control section of the horizontal oscillator 32 is not shown in FIG.
Start adjusting to phase 3. This ringing voltage of increasing amplitude occurring in the retrace capacitor OR is caused by the winding of the flyback transformer and the control section of the inductor Ll! c to the base of transistor Tri r3, making it conductive, thereby cutting off transistor Tri of output switch S1. The ringing voltage v3 of increasing amplitude therefore begins to synchronize the shutoff of the switch S1 to the phase of the output of the horizontal oscillator 32.

As the voltage Vb rises, the already properly phased oscillator 32 controls the switching of the horizontal drive transistor Q5 to supply a correctly phased base current i3 to the horizontal output transistor Q4. The ringing voltage of increasing amplitude causes transistor Q1 to conduct, thereby disenergizing the multivibrator circuit of resistors R1-R4 and capacitor C2 while simultaneously energizing regulator control circuit 22. When regulator control circuit 22 is energized, voltage v3 rises smoothly to its nominal steady-state conduction value.

When switching the television receiver from normal operation to standby operation, this transition is a controlled transition, in which the horizontal output transistor Q4 is continuously and safely brought into saturation, and upon receiving the off command signal, the remote control transistor Q2 is shut off. and stops the operation of the horizontal drive transistor Q5. If transistor Q2 suddenly shuts off during the retrace period, the drive transformer T
The current induced in the winding W++ of 2 from 1ira becomes higher than the current induced from wc, and the horizontal output transistor Q4 continues to shut off until the end of retrace and then remains in continuous saturation.

The operation of the 5rcos type power supply 20 is performed at the low free-running frequency described in the above-mentioned British published patent specification for the first few milliseconds after the off command signal, but the capacitor C1 in FIG. 1 is sufficiently discharged and the transistor Q1 is cut off. If the resistance R1-R
The multivibrator circuit of 4 and capacitor C2 is energized to increase the operating frequency of the 5 ICOS switches Sl, S2 to a free-running frequency close to the horizontal deflection frequency, as described above.

The standby circuit configuration of FIG. 1 described above also provides protection against short circuits and overloads. switching transistor Q
2 is controlled solely by an on/off command signal supplied from the remote control circuit 30, and when this transistor is conductive, it is kept in saturation by the base current supplied from the holding line 26. If there is a short circuit or overload, the voltage Vb will be approximately 6.5
Voltage Vb drops below Vb, shutting off the remote control switching transistor Q2, and putting the television receiver and the 5ICOS type power supply 20 into standby mode operation, but in this standby mode operation, the voltage Vb completely drops and an overcurrent condition occurs. prevent it from continuing. In this way, no matter how many times this television receiver is tried to change to normal operation, it will normally return to standby mode operation unless the overload operating condition is eliminated.

An example of horizontal drive transformer T2 is as follows.

Magnetic core - cylindrical 30 x 6 layers, material N27゜W, -0,
350 turns of 2mm wire, 4mH.

WIl-0.4mm electric wire 80 turns, 2004H.

Wc-0.2mm electric wire 160 turns, 800gH.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the power supply and deflection circuit of a television receiver having a standby remote control circuit embodying the present invention;
The figure shows the waveforms of the circuit in Figure 1 in normal mode operation, Figure 3 shows the waveforms of the circuit in Figure 1 in standby mode operation, and Figure 4 shows a detailed example of the output circuit of the 5IGO9 type power supply. FIG. 20... Switching power supply, 21... Deflection generator, LH... Deflection winding, 27... Sweep switch, 32... Oscillation means, Q2... Mode switching means .

Claims (1)

[Claims] (1) oscillating means; a deflection generator including a deflection winding and a sweep switch; a switching power supply coupled to the deflection generator for supplying power; mode switching for operating the deflection generator and the switching power supply in a normal mode in response to a first command signal, and operating the deflection generator and the switching power supply in a standby mode in response to a second command signal; and; in the normal mode, the sweep switch operates on and off in synchronization with an oscillation signal from the oscillation means to generate a scanning current in the deflection winding and return it in the deflection generator. The switching power supply repeatedly turns on and off in response to the retrace pulse, and supplies power in synchronization with the retrace pulse. Also, in the standby mode, the sweep switch A television display device configured to conduct continuously regardless of the operation of the oscillation means and cause the switching power supply to self-oscillate regardless of the absence of the retrace pulse.