FI74570C - TELEVISIONSPRESENTATIONSSYSTEM. - Google Patents

Description

74570

The present invention relates to a television display system according to the preamble of claim 1. The invention can be used in return-controlled main power supplies, and in particular in a single conversion system (SICOS) power supply as described in GB Application Publication No. 2,094,058 A, published September 8, 1982.

Several types of television standby circuits 10 are known. For example, a small mains transformer is known which supplies power to the remote control circuits of a television receiver and a relay which switches the television receiver on and off. Such a standby circuit can consume only about 6 watts, but is a relatively expensive implementation of a standby-15 power supply.

Another type of standby circuit is a switchable type power supply with an integrated circuit (IC) as a controller, such as a TDA 4600 control circuit IC, and a relay that disconnects most of the secondary voltages of the switching type power supply during standby mode. The switching type power supply operates at a frequency of about 70 kHz during standby to achieve the required large control range. However, the standby power consumption of such a system is relatively high between 10 -20 w.

25 Another type of standby circuit is a mains transformer connected to a switching type controller without a relay. During standby, the remote control circuit turns off the power to the horizontal oscillator. The use of a mains transformer is a relatively cumbersome implementation as a standby circuit structure.

The television display system according to the invention is characterized by what is set forth in the characterizing part of claim 1. One feature of the standby circuit included in the invention is the initiation of a standby function by short-circuiting the horizontal line switch, for example, by keeping the horizontal terminal transistor 35 continuously saturated during standby mode. When a main power supply such as the above-mentioned SICOS power supply is used, the short-circuit switch causes the SICOS power supply to oscillate freely around the horizontal deflection frequency with an operating cycle ratio of approximately 5 line and return time slots. During standby, power for the remote control circuit flows through a shorted line switch from the secondary winding of the return transformer. Standby power consumption can be less than 10 watts and typically about 6 watts. The operating power of the remote control circuit can be 10 about 1.5 w at a voltage of 12 v.

In the drawing, Fig. 1 shows a television power supply and a deflection circuit having a remote control standby circuit embodying the invention, Fig. 2 shows waveforms associated with the circuit of Fig. 1 during normal operation, Fig. 3 shows waveforms associated with the circuit of Fig. 1 during standby operation, and Fig. 4 shows a detailed embodiment of the power supply output circuit-20.

In Figure 1, the SICOS power supply 20 described in the aforementioned GB application operates to transfer energy from an unregulated B + supply terminal to a plurality of television receiver load circuits connected to the secondary windings of the return transformer T1, including a high voltage winding high anode load 33. During normal operation, the horizontal return pulses generated by the horizontal deflection generator 21, the voltage V3 shown in Fig. 2c, are transformer-connected 30 from the secondary winding W2 of the return transformer T1 to the primary winding W1.

From the tap of the primary winding W1, the positive return pulses are peak rectified by a diode D1, filtered by a capacitor C1 and fed to the SICOS controller control circuit 35 22 along the signal line 34. The controller control circuit 22 is synchronized with respect to the horizontal offset by a return pulse voltage applied along signal line 29 to generate pulse width modulated signals 23 having a duty cycle that varies with variations in the return pulse voltage amplitude. The pulse width modulated signals are input to the pulse width modulators S1 and S2 of the input of the SICOS power supply 20 to the spool switch 24. Each switch comprises a transistor, Tri or Tr2, having an opposite diode, not shown in Figure 1, connected between its collector and emitter electrodes. By pulse width modulating the operation of switches S1 and S2, the return pulse amplitude is kept relatively constant as the load and B + voltage conditions vary.

The positive voltage developed across the capacitor C1 keeps the transistor Q1 saturated, thus bringing its collector voltage to the ground 25 potential and biasing the diode D10 in the blocking direction. On the secondary side of the return transformer T1, the standby transistor, Darlington tran-20 transistor Q2, is kept saturated with the base current flowing from the holding rail 26 through the resistor R9 and the zener diode D5. Thus, the horizontal line switch 27 and the horizontal control transistor Q5 are connected to the ground ground 28 by the conductive remote control switch Q2.

The waveforms of Figures 2a-2c show the normal operation of the SICOS power supply and horizontal deflection circuit of Figure 1. Figure 2a shows the switching voltage VI of the SICOS power supply 20 at the junction of the terminal switches S1 and S2. The dashed waveforms in Figure 2 indicate the control range of the power supply. 30 Fixed-wave waveforms represent waveforms taken at a typical operating point of a power supply.

Figure 4 shows a detailed embodiment of the circuitry of the SICOS power supply 20 of Figure 1. The switch S1 becomes conductive at a controllable moment T4 during the line interval of the horizontal deflection cycle 35, connecting the energy storage coil Li B + to the input voltage terminal. The switch S1 becomes 74570 conductive because near the time T4 the rising edges of the pulse width modulated signal 23 have turned on the transistor Tr4, thus turning off the transistor Tr2 of the switch S2. In order to maintain the current 11 in the main winding L1 of the coil L1, the terminal marked with a point L1 of the winding becomes positive with respect to the terminal not marked with a point, thus biasing the switch S1 in the lead direction of the diode DS1. Now the descending current in the winding Lla flows to the terminal B + of Fig. 1.

10 A positive voltage at the terminal marked L1 at the winding induces a positive voltage at the terminal marked Lie at the control winding to bias the base emitter connection of the transistor Tri in the wire direction. Transistor Tri starts conducting current to its winding Lla when the current il1 in Fig. 2b becomes positive at some point after time T4, but within the line interval T2-T6.

At the end of the line interval, at time To, an adjustable amount of energy is stored in the coil Li. A large part of this energy is then transferred to the load circuits connected to the return transformer T1 during the horizontal return time interval T6-T7.

At time T6, a positive return pulse voltage generated at the terminal marked W1 at the winding W1 of the return transformer T1 is applied to the terminal unmarked at the point Lla of the coil Li, making the terminals of the winding Lla and the control windings L1b and Lie unmarked. Transistor Tr3 becomes conductive, turning off transistor Tri. The diode DS2 30 of the switch S2 now takes a positive current il close to the center of the return interval until the transistor Tr2 starts to conduct when the current il becomes negative. During the return interval, an energy resonance transfer takes place via the return transformer T1 between the coil L1 and the return resonant circuit comprising a capacitor 35 of the capacitor CR and the horizontal deflection winding LH and load circuits connected to the secondary windings W3 and W4 of the return transformer T1.

5,74570

Fig. 2d shows the base current i3 in the horizontal end transistor Q4, which current flows from the winding W6 of the horizontal control transformer T2. Figure 2e shows the current i2 flowing in the winding wc of the control transformer T2. Near het-5 ke To, the horizontal control transistor Q5 is turned on, generating a blocking base current i3, which turns off the horizontal terminal transistor Q4 at time T1. Also, starting near the time To, a current i2 is generated which charges the capacitor C8 through the diode D2. The currents i2 and i3 during normal operation thus develop the switching function of the horizontal control transistor Q5.

To switch the television set to standby mode, the remote control circuit 30 supplies a ground ground potential of about 1 second as a SHUT-OFF command-15 signal to the base of the remote control switching transistor Q2 via the control rail 31. When the transistor Q2 is turned off, the current in the winding W2 of the return transformer T1 is forced to flow to the ground ground 28 through the winding Wc of the horizontal control transformer T2. When the conventional current i 1 'flows out of the terminal marked at the point of the return transformer winding W2, the return path of this current is through the horizontal terminal transistor Q4 to the terminal marked at the winding point of the control transformer T2 and then through the diode D2 to charge the capacitor C8.

When the conventional current i ^ 'flows out of the terminal not marked at the point of the return transformer winding W2, the return path passes through the diode of the Darlington transistor Q2, the attenuation diode D7 of the line switch 27 and the diode formed by the base collector connection of the horizontal terminal transistor Q4.

The positive current i ^ induces a horizontal control transformer T2 in the winding for the positive base current i ^ for the horizontal terminating transistor Q4. The current i ^ keeps the horizontal transistor Q4 conductive. Transformer T2 therefore acts as a step-up transformer that generates a positive feedback from the output of transistor Q4 to keep the transistor saturated.

6 74570

During the standby state, the transistor Q4 is either in the conduction state in the saturated conduction state or in the blocking collector conductivity state when the attenuator diode D7 is also conducting. These conditions effectively produce a short-circuited line switch 27 that connects the terminal of the return transformer winding W2 to the terminal marked with the control transformer winding Wc. When the line switch 27 is constantly short-circuited, the return resonant circuit is prevented from forming, thereby shortening the return pulse voltages. The supply voltages through diodes D4 and D6 drop to zero as well as the supply voltage and current through the holding rail 26. As a result, the remote control transistor Q2 remains switched off even after the above-mentioned switch-off command signal interval of one second.

15 The voltage across capacitor C4 is a source voltage of 12V

to the supply rail which supplies power to the remote control circuit 30 and the horizontal oscillator 32. This voltage is generated in standby mode via diodes D2 and D3 from the positive current i1 'flowing in the control transformer winding 20 WC as current 12 »The horizontal oscillator 32 is in standby mode on the television receiver as will be explained later. Darlington transistor Q3 acts as a side current regulator to limit the voltage across capacitor C8.

25 On the primary side of the return transformer T1, when the return pulses collapse at the start of the standby operation, the SICOS power supply 20 starts to operate freely oscillating. The collapse of the return pulse voltages prevents the operation of the control circuit 22 and turns off the transistor Q1. When the transistor Q1 is samra-30, the RC network comprising the resistors R1-R4 and the capacitor C2 is tuned to form an unstable multi-vibrator arrangement with the SICOS switches S1 and S2.

The waveforms of Figure 3 show the waveforms associated with the circuit of Figure 1 in standby mode. As shown by the voltage VI in Fig. 3a, after the drive t1, the switch s1 of the SICOS power supply 20 conducts. Also close to time t1, the left plate of the capacitor C2 is positive relative to the right plate. As a result, when the switch S1 becomes conductive, the capacitor C2 begins to discharge through the resistors R2 and R3, as shown in Fig. 3b for the falling voltage 5 on the collector of the transistor Q1 after a moment t1.

The switch S1 of the SICOS power supply 20 remains conductive due to the regenerative effect formed by the control windings L1b and Lie in Fig. 4. As shown in Fig. 10 3a, the switch S1 remains conductive until the time t1, when the transistor Tri of the switch S1 starts to turn off. At time t1, the transistor Tri is off and the switch S2 is turned on due to the conductivity in the diode DS2, thus bringing the voltage VI to the ground potential.

At time t1, the capacitor C2 is charged to the opposite polarity of the polarity delta so that the right plate of the capacitor is positive with respect to the left plate. When the positive right plate is locked to ground by switch S2, the base collector connection 20 of transistor Q1 becomes biased in the line, locking the voltage V2 just below ground potential between moments t4 and t6 in Figure 3b, capacitor C2 discharges through transistor Q1 base collector connection + resistor R2. Near time t6, the voltage across capacitor C2 25 changes its polarity in the bias blocking direction of the base collector connection of transistor Q1. Capacitor C2 begins to charge from terminal B +, positively charging the left plate of the capacitor relative to the right plate.

At the moment of Fig. 3b, the capacitor C2 is sufficiently charged to bias the diode D10 in the line direction and to turn on the control transistor Tr4 of the SICOS power supply 20. Switching on the control transistor Tr4 turns off the output transistor Tr2. When Tr2 turns off, the diode DS1 of the switch S1 turns on to take the current from the main winding L1 of the coil Li of Fig. 4. As a result, the voltage VI increases at the voltage level B +, as shown in Fig. 3a.

The duration of one full free oscillation of the switches S1 and S2 is, by way of example, 70 microseconds, which is close to the duration of the horizontal deflection TH = 64 microseconds.

5 The 70-second period of free oscillation is chosen to be short enough so that it is in an unheard-of standby state for most people. The setting of the free oscillation period can be performed by setting the value of the resistor R2 of the unstable multi-vibrator.

Fig. 3c shows the current il in the winding of the return transformer T1 during the standby operation. Since the windings W1 and W2 are tightly connected to each other and have approximately the same number of revolutions / current in the winding W2, and thus the collector of the horizontal terminal transistor Q4 in standby mode has approximately the same shape and amplitude as the current i1. Compared to the currents i1 and i1 'during normal operation, the currents i ^ and i ^' during standby operation have substantially decreased. The power consumption of the SICOS power supply 20 during standby mode is thus relatively low by way of example 6W.

Figure 3d shows the voltage V4 across the remote control switch transistor Q2 during standby mode. Between time t0 and time t2 during the time interval in which the currents in the windings W1 and W2 of the return transformer T1 are negative, the diode of the Darlington trans-25 transistor Q2 is biased in the line direction, locking the voltage V4 to the ground ground potential. Between times t2 and t3, the currents i ^ and i ^ 'are positive and rise upwards. During this time, the current in the winding Wc of the transformer T2 is positive, biasing the diode 30 D2 in the wire direction and charging the capacitor C8 to a voltage of about 20V. During this time interval, the voltage V4 is positive and locked to a voltage level formed by the voltages generated across the winding Wc of the control transformer T2 and the capacitor C8.

Near the moment t ^, the switch S2 of the SICOS power supply 20 becomes conductive, starting with the negatively inclined portion of the currents i ^ and i ^ '. After time t3, the current i 1 'flowing into the winding Wc of the control transformer T2 causes the polarity of the voltage generated across the winding Wc to change. As a result, the voltage V4 decreases from the moment 5 t to the moment tj. current i ^ 'to zero crossing point. At time tg, the current i ^ 1 becomes negative by biasing the diode of the Darlington transistor Q2 in the wire direction, again locking the voltage V4 to the ground ground potential.

Since the line switch 27 is short-circuited during the standby-10 mode operation, the voltage generated across the return transformer winding W2 is the same voltage V4 shown in Fig. 3d, but at a different zero volt AC reference level. Thus, during standby operation, the peak-to-peak voltage across the winding W2 is, for example, approximately 25 V compared to exemplary 900 V during normal operation, i.e., the peak-to-peak voltage has dropped to about 3% of the voltage during normal operation.

The conduction of the horizontal control transistor Q5 is blocked by the forward bias voltage of either diode D8 or diode D9. Therefore, the operation of the horizontal oscillator 32 during the standby mode does not interfere with the free oscillation operation of the SICOS power supply 20.

The standby power for the remote control circuit 30 and the balance 25 chaoscillator 32 is derived from the winding Wc of the horizontal control transformer T2 as a current ^ 2 · which charges the capacitor C8 and the capacitor C4 during the standby operation. The average of the positive part of the current i3, shown in Figure 3f, is about 150 mA, resulting in about 1.8W of operating power at the output of the 12V controller. The positive current i1 in the winding W1 of the transformer T2, which current is shown in Fig. 3e, is induced by the current i3. The current i ^ has a higher amplitude because the winding Wb has only half the twist number of the winding Wc. The inductance of the winding Wb 35 may be, for example, 200 μH, and thus the inductance Wc of the winding 10,74570 may be as much as 800 μU.

Resistors R7 and R8 equalize the base current i ^. Through the resistor R7, some energy is stored in the winding W to increase the base current i1 when D2 5 goes out. The horizontal terminal transistor Q4 is safely held in saturation until the current through its collector is zero.

To return the television receiver to normal operation, the remote control circuit 30 supplies a positive pulse, a START command signal, to the base of the switching transistor 10 of the switching transistor 10 via the control rail 31 for about 1 second until sufficient holding current for the transistor is next obtained from the holding rail 26. grounding 28 directly through the switching transistor Q2, supplying ground potential to the emitter of the horizontal terminal transistor Q4. As a result, the current i ^ 1 in the return transformer winding W2 is bypassed to ground by the transistor Q2 away from the control transformer T2 winding Wc · As a result, the current i3 decreases significantly and the horizontal terminal transistor Q4 does not conduct continuously saturated.

The operation of the SICOS power supply 20 changes to a start-cycle operation in the same manner as described in the above-mentioned P. Haberlin GB application. This cycle is controlled by the return overshoot oscillation until the return voltage connected to the wire winding W1 of the return transformer T1 en-25 is high enough in amplitude to restart the SICOS controller control circuit 22. When the controller control circuit is restarted, the shutdown of the output switch SI is synchronized with the horizontal return. At the same time, the return pulse voltage produces saturation of the transistor Q1, preventing the operation of the multivibrator network of the resistors R1-R4 and the capacitor C2.

When switching from the standby mode "on" to the operation, the current i3 changes after being induced by the winding W of the control transformer T2 and induced by the current of the winding W. In the same way as when switching from "on" operation to standby mode, the current is absorbed after being induced by the winding Wc induced by the winding W. 117570. To perform these transitions safely without damaging the horizontal transistor Q4, the switching cycle of the transistor Q4 is not interrupted during the transitions. Transistor Q4 is not turned on when a significant positive voltage V3 is present on its collector.

In the standby state, the horizontal oscillator 3L operates, but it is only in circuit with the base of the horizontal control transistor Q5 when the voltage V4 is low. The current i ^ ', when the voltage V4 is low, flows in the negative direction from the diode of the Darling-10 ton transistor Q2. Thus, although the switching signals are applied to the base of the control transistor Q5 in the standby mode, only a small negative current i 1 flows and does not interfere with the operation of the transistor Q4.

When the current i ^ 'becomes positive, the voltage V4 15 rises. Conduction by the collector of transistor Q5 is cut off by diodes D8 and D9. The positive current i 1 current keeps the transistor Q4 biased to saturation.

When the television receiver is switched from the standby-20 state to the "on" operation, the transistor Q2 is switched to saturation. Immediately after receiving the START command signal, the voltage V 1 is at zero volts, conducting a zero current i 1 to control the horizontal transistor Q4. The SICOS power supply circuit 20 continues to operate freely, 25 as during standby mode. The return circuit L1, CR oscillates to produce an amplitude-increasing voltage V3 at the return frequency during the time interval t1-T1 of Fig. 3.

The automatic frequency and phase control portion of the horizontal oscillator 32, not shown in Fig. 1, a-30 phases the output of the oscillator to the phase of the overshoot voltage V3. The amplitude-increasing overshoot voltage generated across the return capacitor CD is connected to the base 35 of the transistor Tr3 by the return winding W1 and the control winding Lie of the coil L1 to turn on this transistor, thereby turning off the transistor Tri of the output switch S1. As a result, the crossover oscillation voltage V3 increasing in amplitude begins to synchronize the switching off of the switch S1 to the output phase of the horizontal oscillator 32.

As the voltage increases, the already correctly phased oscillator 32 controls the connection of the horizontal control transistor Q5 to supply the correctly phased base current i4 to the horizontal terminal transistor Q4. The amplitude of the crossover oscillation voltage turns on the transistor Q1, thereby preventing the operation of the multivibrate-10 market arrangement of the resistors R1-R4 and the capacitor C2 and at the same time starting the controller control circuit 22. As long as the controller control circuit 22 is started, the voltage V3 increases steadily to its nominal steady state.

When the television receiver is switched "on" from operation to standby mode, the transition is controlled and safely puts the horizontal transistor Q4 into a saturated continuous conductivity mode. When the "shutdown" command signal is received, the remote control transistor Q2 is turned off, thus preventing the operation of the horizontal control transistor Q5.

20 If the transistor Q2 happens to be switched off during the return, to the winding W of the control transformer T2, from the winding W

The current induced by D cl is higher than the current induced by the winding Wc. Horizontal transistor Q4 remains switched off until the end of the return. Thereafter, transistor Q4 is held-25 in continuous saturation.

For the first few milliseconds after receiving the POWER OFF command signal, the operation of the SICOS power supply 20 is at the lower free oscillating frequency described in P. Haferl, GB-A-30, cited above. When the capacitor C1 of Fig. 1 is discharged enough to turn off the transistor Q1, the operation of the multivibrator arrangement of the resistors R1-R4 and the capacitor C2 is inhibited and increases the operating frequency of the SILOS switches S1 and S2 to a free oscillation frequency close to the horizontal deflection frequency.

74570

The standby circuit arrangement just illustrated in Figure 1 also provides short circuit and overload protection. The switching transistor Q2 is controlled only by the ON-OFF command pulses 5a generated by the remote control 30. When the transistor is turned on, it is kept in saturation by the base current supplied by the holding rail 26. A short circuit or overload that produces a voltage drop below about 6.5 V turns off the remote control transistor Q2 and puts the television receiver-10 receiver and SICOS power supply 20 into standby mode. In standby mode, the voltage completely collapses, preventing excessive current from continuing, so the television receiver usually enters standby mode under the influence of a continuous overload mode, even when 15 repeated attempts are made to turn on the television.

An example of a horizontal control transformer T2 is the following:

Heart = cylindrical 30 x 6 mm, material N27; 20 W = 350 turns of 0.2 mm wire, 4 mH; = 80 turns of 0.4 mm wire, 200 μH; W = 160 turns of 0.2 mm wire, 800, uH.

c /

Claims (13)

14 74570 A television display system responsive to an ON-OFF command signal state and comprising a deflection winding, a deflection generator including a line switch operating during a normal condition to generate a sweep current to the deflection winding, a power supply switching the normal power, the deflection-synchronized deflection power -10 for a television display system, characterized by means (Q2, W1, Wc) connected to the deflection generator (21) and responsive to the ON-OFF command signal to provide continuous guidance of the line switch (Q4) upon receiving the OFF signal from the command signal. to change the operation of the switching power supply (20) to standby mode. A television display system according to claim 1, characterized in that the switching power supply (20) oscillates freely in the standby mode to generate power at a substantially reduced power level. Television display system according to claim 2, characterized in that the deflection generator (20) includes a return resonant circuit (C0, LTI) KH for generating a return pulse voltage and that the switching power source (20) includes an inductance (W1) connected to the return resonant circuit (W1). CR, LR) to transfer energy between them. Television display system according to claim 3, characterized in that the switching power supply (20) comprises output switching means (S1, S2) of the voltage source (B +) connected to the source (B +) and the inductance (W1), and a control circuit (S1). 22) to produce deflection-synchronized operation of the output switch means during a normal state, the control circuit (22) being dependent on the absence of a return pulse voltage to produce a free oscillation of the output switch means (S1, S2). A television display system according to claim 1, comprising an input voltage source with a switching power supply connected to said source, characterized by a power transformer (T1) having a first winding (W1) connected to the switching power supply (20) and a second winding (W2) connected a deflection generator (21) for transferring power from the source to the deflection generator 10 during normal operation, and a standby power supply (W, D2, C8) for generating a supply voltage during standby mode while power is flowing to the standby power supply via a short-circuit intermediate-15 with them. A television display system according to claim 5, characterized in that the switching power supply includes control circuitry which, in the SWITCH mode of the command signal, generates a free oscillating voltage of the switching power supply to generate a voltage of varying polarity over the secondary winding (W2) of the power transformer. A television display system according to claim 6, characterized in that the means responsive to the ON / OFF command signal comprises a controllable switch (Q2) in parallel with the standby power supply (Wc, D2, C8) for controlling the power past the standby power supply during normal operation. A television display system according to claim 6, characterized in that the switching power supply (20) includes an inductance (LI) for storing energy therefrom from the input voltage source (B +), wherein the return pulse voltage generated by the deflection generator is applied to the inductance during normal operation. 16 74570 Television display system according to claim 1, 5 or 8, characterized in that the switching power supply comprises output switching means (Tri, Tr2) connected to the input voltage source (B +), a reactive network (R1, R2, R3, R4, C2), coupled to the output switching means, and means (Q1) responsive to a signal indicating the absence of return pulse development to activate the reactive network to produce free oscillating operation. A television display system according to claim 9, characterized in that the switching power supply control circuit (22) responds to a deflection frequency signal (29) during normal operation to cause the switching power supply to operate in sync with the sweep current development and that the reactive network (R1, R2, R3, R4, C2) produces a freely oscillating operation during the standby mode at a frequency close to the deflection frequency. Television display system according to claim 5, characterized in that said short-circuit path is produced by continuous guidance of the line switch (Q4) and in that the means responsive to the ON-OFF command signal comprises a second transformer (T2) having a first winding (W1) connected to the line switch control terminal 25 and having a second winding (W) connected to the line switch output terminal and the standby power supply to provide positive feedback to maintain continuous line switch conduction. A television display system according to claim 11, characterized in that the means responsive to the ON / OFF command signal comprises a controllable switch (Q2) connected to the line switch (Q4) for controlling current past the second winding (w) of the second transformer (T2) during normal operation, c A television display system according to claim 11 or 12, characterized by a deflection oscillator (32) connected to the third winding (W_) of the second transformer (T2) to produce a deflection frequency switching of the line switch d (Q4) during normal operation. 18 74570