CN1044425C - Television receiver with apparatus for evade damage of point of light and control afterglow - Google Patents

Abstract

A television apparatus includes a kinescope having a high voltage supply (B+), a deflection circuit, a cathode driver amplifier and a control circuit for controlling operating modes of the receiver. A first means (TR17) responsive to a turn-off command signal (STBY) from the control circuit disables the high voltage supply (B+) and initiates turn off of the deflection circuit at a controlled rate. Concurrently, a second means (DR10,DR11) responsive to the turn-off command (STBY) applies a turn on drive signal to at least one electron gun of said kinescope for discharging high voltage therefrom. Advantageously, during turn-off the high voltage is drained from the kinescope as the displayed raster collapses thus providing benefits such as the safety feature of having a fully discharged kinescope, avoidance of kinescope spot burn and prevention of kinescope after-glow.

Description

Have luminous point and burn the television receiver of protection and twilight sunset inhibition facility

The present invention relates to television receiver, the television receiver that is specifically related to is provided with in it in order to the appearance that prevents some visible artifacts (for example luminous point burns or twilight sunset) unlikely from normal " RUN " mode of operation to " standby " or the facility that occurs of " shutdown " mode of operation transition period.

During the television receiver normal running, electron beam energy distributes and traverses the sizable area in picture tube fluorescent screen.When this receiver is shut down or is switched to the standby operation mode, must be enough to prevent to produce concentrate with accelerated electron beam and electron beam energy at the sharp strive forward potential decay of each electrode of picture tube and can damage the picture tube phosphor or produce before the undesirable visible artifacts such as twilight sunset, the sweep current in level and vertical deflection winding just can disappear.

At being entitled as of Peter E.Haferl " Electron Beam Suppression CircuitFor A Television Receiver ", on December 11st, 1984 laid-open U.S. Patents US4; 488; described the example of a television receiver in 181, these facility have operation and standby operation mode and are provided with and burning the protection facility from the operation or the mode of normally watching to the picture tube luminous point in the transition period of standby mode (at this moment some circuit of the receiver still be powered).

In an exemplary embodiment of Haferl receiver, deflection generator and deflection winding are coupled, and in order to produce sweep current, traverse the electron beam scanning of picture tube fluorescent screen with generation.A remote control circuit produces opens (opening)/pass (breaking) command signal, so that television receiver is switching between normal operation and standby operation mode.One first this command signal of switching response and can not normally produce sweep current when this command signal presents " shutoff " state is to forbid the normal scan of electron beam.A second switch also responds this command signal, applies a stopping potential to picture tube anode when " shutoff " state appears in this command signal, to suppress the generation of electron beam before can not producing sweep current.

Switching to when shutdown at receiver from unlatching is a kind of fine and effective method that prevents that the picture tube luminous point from burning in the Haferl technology that the anode of picture tube applies cut-off bias.Another characteristics of Haferl receiver are to be provided with in order to suppress the facility of twilight sunset under so-called " warm start " operation of receiver state.Specifically, the Haferl receiver is provided with the facility that the fluorescent screen anode voltage is set up in time-delay.Even if this time-delay is guaranteed under the still awfully hot and quite high still maintenance situation of high-voltage anode voltage of negative electrode just in case open the luminous point that this television receiver also be cannot see electron beam.And when receiver between standby mode and normal operation mode during Rapid Cycle (i.e. " warm start " state), may this thing happens.

Here admit when receiver switches between operational mode and standby mode to require to have and suppress luminous point and burn facility with afterglow effect, and require to guarantee the high voltage that during standby mode picture tube high voltage anode circuit is not dangerous thereby the characteristics with fail safe additionally are provided.Purpose of the present invention satisfies these requirements exactly.

Embodying a kind of television receiver of the present invention comprises: a picture tube, high voltage source, a picture tube driving amplifier, a deflection circuit and a control circuit that supplies picture tube to use.One first device, response be from " shutoffs " command signal of control circuit, and high-voltage power supply is not worked and with a kind of shutoff of controlling speed startup deflection circuit.One second device, response " shutoff " command signal applies " unlatching " drive signal so that high voltage discharges thus at least on an electron gun of picture tube.

Useful is that along with showing that grating slowly disappears, high voltage is released from picture tube, and following benefit is provided whereby: the characteristics of (1) fail safe, and picture tube discharges fully, and (2) avoid the picture tube luminous point to burn, and (3) prevent the afterglow effect of picture tube.

The object of the present invention is to provide a kind of television receiver; this receiver has luminous point and burns protection and twilight sunset inhibitory action when switching between operational mode and standby mode, with guarantee during the standby mode in the picture tube high-tension circuit not dangerous high voltage.

The present invention has been applied to a kind of television receiver that luminous point burns protection and twilight sunset inhibition facility that has, and this television receiver comprises: a picture tube; A driving amplifier is in order to drive above-mentioned picture tube; A high voltage source; A deflection circuit; A control circuit turn-offs command signal (" operation/standby ") in order to produce, and suspends to make this receiver during transition interval when operational mode becomes standby mode at this receiver; And above-mentioned high-voltage power supply is not worked and start the device that above-mentioned deflection circuit turn-offs with a kind of controlled speed in order to respond above-mentioned shutoff command signal.

According to the present invention, this receiver is characterised in that: driving amplifier comprises first and second amplifiers.First amplifier has: a signal input part, in order to receive image representation signal (G-Y; Y); A control input end is in order to receive control signal (G); And an output, be coupled on the electron gun of picture tube.First amplifier response is applied to first level of the control signal (G) on the control input end, with so that be applied to image representation signal (G-Y on the above-mentioned signal input part; Y) any value blasting makes the amplifier of winning can make electron gun produce maximum output electron beam level.Character signal (GREENDRIVE) and shutoff command signal (operation/standby) on the second amplifier response screen display, this two signal is applied to first (GREEN DRIVE) of second amplifier respectively) and second input on, in order to produce first level of control signal (G).Second amplifier response turn-offs command signal (operation/standby), during transition interval, make character signal on the above-mentioned screen display device (GREEN DRIVE) blasting, so that control signal (G) presents first level, in first amplifier, make image representation signal (G-Y during the transition interval whereby, Y) blasting, to produce maximum output electron beam level, and carry out electrion from picture tube, and on picture tube, produce the demonstration of uniform luminance, to prevent image representation signal (G-Y across whole demonstration grating; Y) amplitude characteristic of character signal (GREENDRIVE) unlikely luminous point that causes during transition interval burns and damages picture tube or on the screen display.

These characteristics of the present invention is described with reference to the accompanying drawings, and numbering identical in the accompanying drawing is represented components identical.

Fig. 1 and Fig. 2 part illustrate with the block diagram form and realize television receiver schematic diagram of the present invention,

Fig. 3 illustrates the timing diagram of the Vcc power level on the switch mode power controller that startup, standby, operation and " operation/standby " transition period be applied to receiver,

Fig. 4 illustrates the corresponding timing diagram that is applied to the B+ voltage level on the elementary winding of receiver kickback transformer with Fig. 3,

Fig. 5 illustrates a V _IThe pulse envelope figure of electric current in the elementary winding of power transformer at place,

Fig. 6 illustrates operational mode and " operation/standby " transition period horizontal time-base V _HPulse envelope figure,

Fig. 7 illustrates the timing diagram of logical signal STBY (" or inoperative ") and XRP,

Fig. 8 A and Fig. 8 B illustrate the square and the circuit diagram of crt driver circuit details in the receiver illustrated in figures 1 and 2.

In order to simplify accompanying drawing, Fig. 1 illustrates and the relevant receiver section of power transformer LP36 primary side, and Fig. 2 illustrates the receiver section relevant with this transformer secondary, and Fig. 8 A and Fig. 8 B illustrate the Video processing details of receiver section illustrated in figures 1 and 2 respectively.

Among Fig. 1, television receiver can be worked between interchange 90V and 250V by North America and European voltage level by ac mains 22 power supplies.This power supply is by bridge rectifier 24 full-wave rectifications, by current-limiting resistance RP03 and capacitor CP06 filtering, so that a unregulated input voltage V to be provided _IN, and it is applied on the terminal of elementary winding W1 of power transformer LP36.Another terminal of winding W1 is coupling on the collector electrode of power transistor TP29, and this transistor is driven by the output of switch mode power controller 20 (for example model TEA2260 of SGS Thomson Microtronic A/S).Each pin of this controller number as shown in FIG..

Controller 20 has two kinds of modes of operation.Under slave mode, controller 20 responses are from the arteries and veins of the width modulated of kickback transformer FBT secondary winding feedback, and as shown in Figure 2, the control of the width of pulse " is never regulated input voltage V _INTo the adjusted output of B+ of transformer LP36 " the energy coupling.B+ output is coupled on the elementary winding of kickback transformer FBT, in order to drive horizontal sweep and power supply is coupled to only in the load of several work under the television receiver operation mode.Under second mode of operation of controller 20, that is when nothing applied from the width adjusting pulse power supply primary side, that supply adjusting, controller 20 reset into according to a state that the error input is regulated that obtains from power transformer LP36 secondary winding W3.Only regulate by the input of this error and under situation about not having, just to work from the pulse of kickback transformer primary side.Every all these pulses exist, and this error input all is left in the basket.The adjusted output level of controller be provided with under the slave operation mode than higher under second (error input) mode.

Television receiver is started working under standby mode, and is switched to operational mode under the control of microprocessor 82, as shown in Figure 2.Microprocessor 82 and power-supply controller of electric 20 (as shown in Figure 1) all are powered under standby mode and operational mode.

When connecting ac mains 22 first, the V of controller 20 _CCPower supply on the pin 16 is by being coupled to " the not adjusting input voltage V of bridge rectifier 24 outputs _IN" starting current supply with.Be coupling in the V of controller 20 _CCThe capacitor CP28 of pin 16 is by current-limiting resistance RP06 and forward bias diode DP07 charging.In case controller 20 work, its output pulse just will be coupled on the secondary winding W3 from the energy of the elementary winding W1 of transformer LP36 by power transistor TP29.The signal of secondary winding W3 soil is by diode DP28 rectification, and by capacitor CP17 filtering, and process forward bias diode DP08 is coupled to the V of controller 20 _CCOn the input.Like this, after by the electric charge initial start that is applied on the capacitor CP28, controller power supply itself.

During boot sequence, as Fig. 3 and shown in Figure 5, owing to capacitor CP28 charging makes V _CCVoltage ramp rises, when controller 20 becomes operating state and begins to export pulse till.Controller 20 has a plurality of internal limitations circuit, in order to preventing contingent overvoltage or overcurrent when initial, this controller 20 can own shutoff and/or when power supply conforms with power reguirements with its export-restriction on the level of safety.Controller 20 also is provided with soft starting circuit 40, and CP08 is coupled with capacitor, the speed in the time of may increasing in order to limit the continuous impulse amplitude, V _CCThe limit of the minimum value of voltage max is by V _CCObservation circuit 48 and 50 limits.Transship repeatedly by comparator 54 sensings, this comparator 54 is coupled with the reference value of the voltage and current of CSET CP07 and inside.Output current maximum among the power transformer LP36 is by current limliting comparator 56 and 58 restrictions, and these two comparators 56 and 58 are coupled on the current sensing resistor RP32 that connects with power transistor TP29 emitter through resistance R P18.The signal of current sense input is by capacitor CP18 filtering." demagnetizationization " comparator 46 directly and winding W3 be coupled, in order to sensing " zero crossing ".These protective circuits arrive V to the initial delay of pulse usually _CCForce to disappear when being charged to minimum value and in one or more restrictions of pulse and make V _CCAfter the reference level that input limited of arrival by the error amplifier 34 of controller 20.

The reference level of error amplifier 34 inverting inputs is provided by Zener diode DP14, and the above-mentioned reference level at this diode DP14 anode place is coupled on the above-mentioned input of error amplifier through resistance R P16 ground connection and through resistance R P15.When voltage on the winding W3 arrives 8.2V through the step-down of diode DP28 and DP08, Zener diode DP14 punctures, whereby the voltage that is about 2.25V is applied on the error input, compares with the 2.49V internal reference voltage on the normal phase input end that is applied to error amplifier 34.Resistance R P17 is coupling between the output and inverting input of error amplifier 34, comes the specification error Amplifier Gain.

Output driving V when controller _CCArrived a high level and this high level when being enough to make error amplifier output to show to arrive a high threshold value, controller 20 enters " short pulse " (burst) mode, and in its operation of internal modification, to follow the tracks of 90% rather than 100% of this reference level.The V on holding capacitor CP28, the CP17 etc. is ended and is accumulated in the granting of pulse _CCVoltage in a period of time internal leakage fall, when this voltage satisfies this threshold value of 90% till.Controller 20 is obtained original threshold value and output pulse train again, and this makes this output turn back to reference level of 100% or the like.V _CCAdjusted output voltage limit the voltage hysteresis between two threshold values that flounces of a series of rising and decline slope, as among Fig. 3 t1 and t2 two constantly between shown in like that.

Modulator 36,38 is coupled in the output of error amplifier 34, this modulator soft start slope of soft starting circuit 40 slope of voltage and oscillator 42 output voltage that flounces that flounces that also is coupled.Modulation logic and automatic " short pulse " (bursl) generator 44 are coupled in the output of this modulator, and the latter is coupled on the pulse output end of oscillator 42.The slope on above-mentioned slope and pulse duration are set by outer meeting resistance RP09 and capacitor CP09.IS logic level 32 is preferentially the output that is coupled to controller 20 from the input of resistance R P41 and primary side pulse width modulator.But when confiscating pulse by resistance R P41, the output of controller just is coupled in the output of modulator logic element 44.Adjusted pulse from IS logical block 32 is coupled on the logic processor 52, and is coupled on the output transistor 66,68 through forward and negative sense output driver 62,64, and this transistor provides electric current or slave controller 20 output connecting pins 14 leakage currents.

Transistor T P01 is coupling between the current-limiting resistance RP06 and ground of starting current circuit.Capacitor CP28 from ac mains by resistance R P06 and diode DP07 charge electricity and controller 20 begin by from the feedback of the secondary winding W3 of power transformer LP36 to V _CCAfter regulating, the base stage of transistor T P01 rises along with the charging of capacitor CP17 at the voltage at series resistance RP14 and bias resistance RP13 place, makes transistor T P01 conducting then.Discharge from the next charging current inflow place of resistance R P06, the electric current of the resistance R of flowing through P21 (resistance R P21 role is as a mute load in parallel with holding capacitor CP28) also flows into ground discharge.Voltage V has been striden in utilization _CCThis mute load of resistance R P21, variation between different TEA2260 controllers on current loading can be reduced, thereby the circuit design that provides has quite constant time of delay in a scope of controller current loading rated value and under different ac mains voltage condition.

The output of controller 20 is coupled on the base stage of power transistor TP29 through a network (comprising capacitor CP24 and the branch road of being made up of diode DP24, DP26 and DP27 in parallel with it).When the pulse of controller 20 output positive phase, diode DP24, DP26 and DP27 be forward bias all, and the result limits diode drop and is about 2.1V and comes the charging for capacitor CP24.When controller 20 was output as minus phase, the electric charge that harvests on capacitor CP24 helped to remove the electric charge of power transistor TP29 base-emitter, stopped the conducting of TP29 immediately.Resistance R P28 and inductance L P28 offer the pulse of shaping on the base stage of transistor T P29, and resistance R P29 provides bias voltage.On the collector electrode of transistor T P29, limit a damping networking and clamp circuit by diode DP29 and resistance R P31 and with these two capacitor CP29 and CP31 in parallel respectively.

The secondary of power transformer LP36 provides V around level W3 for controller 20, secondary winding W2, W4 and W5 _CCOther adjusted output voltage also is provided in addition.Signal on the secondary winding W2 by capacitor CP51 filtering, provides adjusted B+ to be output as+118V by diode DP50 rectification, to drive kickback transformer FBT.Provided+19V voltage by winding W4, it is by diode DP63 rectification, by capacitor C P64 filtering.Winding W5 provides+24V voltage through diode DP92 and capacitor CP86 in a similar manner.

The output voltage of all secondary winding of power transformer LP36 and V _CCRegulate to the feedback path of error amplifier 34 through the winding W3 that associates by controller 20 together.But the load of these secondary winding can change.For example, when no horizontal pulse was fed to kickback transformer, B+ voltage was non-loaded and keep constant, at this moment V _CCOwing to " short pulse " mode of operation of controller changes.+ 19V voltage also is adjusted to+5V by adjuster 26, so that a constant supply voltage to be provided to microprocessor 82, although be in V under " short pulse " mode at controller 20 _CCBe to be among the variation of rising and descending.

With reference to Fig. 2, Fig. 2 is the extendible portion of power transformer LP36 primary side among Fig. 1.It comprises: each winding of above-mentioned identical sign that uses the power transformer of same reference number.Adjusted B+ voltage from winding W2 is coupled on the elementary winding of kickback transformer FBT.Because of controller 20 was both also being worked under standby mode under the operational mode, so B+ voltage always produces.Flow through the electric current of the elementary winding of transformer FBT by horizontal output transistor 49 control, and 49 of transistor Ts obtain pulse from horizontal oscillator tube 86 and horizontal output driver 88 when operational mode.Clamping diode DC, flyback capacitor CR, horizontal deflection winding YH and S shape capacitor CS are coupled with the elementary winding of horizontal output transistor T 49 and transformer FBT, with controlling level deflection.

Each secondary winding of transformer FBT is coupling in the load of operational mode, and these loads are only energized in horizontal scan period.The load of these operational modes comprises: fluorescent screen anode (representing with CSC usually) is coupled with high-voltage anode supply voltage U; Kinescope driver 84, through diode DL11 and filtering capacitor CL11 be coupled to+the 180V power supply on; And other load (comprise pulse width modulator 92, through diode DL13 and filtering capacitor CL14 be coupled to+the 13V power supply on.

Secondary winding for kinescope driver 84 usefulness provides flyback pulse with signal VP, and this signal feedback is given controller 20, so that the power supply of on-off mode and horizontal sweep simultaneous operation.In such a manner, the electric current among the elementary winding W1 of power transformer LP36 can be cut off during the flyback blanking cycle, so that the energy from transformer LP36 can not influence display by power transistor TP29 the time.Signal VP is coupled on the pulse width modulator 92, and this modulator also is coupled on the adjusted voltage of B+ through the voltage divider of being made up of resistance R P51, RP52 and potentiometer PR52.The pulse of pulse width modulator output is exported to the base stage of transistor T P69 through resistance R P68 and bias resistance RP69, and the width of pulse is along with the level of the input signal that potentiometer PP52 contactor comes changes and changes.

On behalf of primary side, the signal that is imposed on transistor T P69 by pulse width modulator feed back to the level of the adjusted voltage of B+ of controller 20.The elementary winding WP of the collector electrode of transistor T P69 and signal coupling transformer LP42 is coupled its grounded emitter.If supply voltage (the another terminal coupling of P point and winding WP) is arranged on the P point, then transistor T P69 conducting is to apply the pulse of width modulated on the elementary winding WP of signal coupling transformer LP42.RP60 provides bias voltage with winding WP parallel resistor.Return with reference to Fig. 1, feedback pulse is coupling on the subordinate input of controller 20 by resistance R P41 and RP42, and feedback is provided, to regulate B+ voltage under operational mode.Transformer LP42 and power transformer LP36 make the isolated with the ground on " cold " of the primary side (primary side of transformer LP42) of transformer LP36 or chassis " heat " of power transformer LP36 primary side (and/or WS winding of transformer LP42).

In Fig. 2, signal P be by the STBY of microprocessor 82 output lead, when operational mode, be high level, under standby mode, be low level.Signal STBY is coupling on the emitter of transistor T R16, and the base stage of transistor T R16 is by resistance R R15 and the coupling of+5V power supply.+ 5V power supply is obtained by winding W4+19V power adjustment, all works under standby mode and operational mode, returns microprocessor 82 power supplies.When entering operational mode, microprocessor 82 pulls down the STBY signal and is low level, allows transistor T R16 conducting.The collector electrode of transistor T R16 is coupled to by resistance R R16 on the base stage of PNP transistor T R17, by the resistance R R17 relevant biasing with transistor T R17, transistor T R17 with from the winding W5 of power transformer LP36+coupling of 24V power supply.When STBY was low level, signal P was+24V, and when STBY is high level (that is under standby mode), signal P is an earth potential.

Signal P supplies with energy the V of signal transformer winding WP and process diode DP05 supply level oscillator _CCInput, the negative electrode of diode DP05 provides signal FK.Signal FK is coupled to the V of horizontal oscillator tube 86 through resistance R P07 _CCOn the terminal, this V _CCInput is by holding capacitor CI21 filtering.Signal FK is the branch pressure voltage of resistance R V04 and RV02.The base stage of transistor T V02 is coupling on the tie point of resistance R V04 and RV02, and its collector coupled is on the X ray protection input XRP of integrated circuit IL01, and this integrated circuit includes horizontal oscillator tube 86.The XRP input stops the output of horizontal oscillator tube.XRP imports normally high level, but it is a low level when signal P is high level.The XRP signal can stop the method for output of horizontal oscillator tube a lot.In the present embodiment, this function is shown by the internal signal SCR that is coupling in horizontal oscillator tube 86 outputs that usually this signal also is coupled to the V of horizontal oscillator tube by an internal resistance _CCOn the end.

When signal P is low level, not conducting of transistor T V02 between standby period.When transistor T V02 did not make the XRP input grounding, it was high level that XRP input is driven by signal XR, and signal XR is that the winding W4 by power transformer LP36 draws.Winding W4 is by current-limiting resistance RP87 and series resistance RV01 and diode DV01 coupling.The negative electrode of diode DV01 is coupled on the XRP input of integrated circuit IL01, and this integrated circuit includes horizontal oscillator tube 86.Integrated circuit IL01 can adopt the Mitsubishi type M52043SP in the pal mode television receiver.Signal on the diode DV01 negative electrode is by capacitor CV01 filtering, and is coupled to ground through resistance R V05.

With reference to the timing diagram of Fig. 3 to Fig. 7, be arranged to limit transient mode between operational mode and the standby mode in the transition between operational mode and the standby mode, finish this transient mode in the output of using controller 20 forward, with the blocking-up horizontal pulse.Two kinds of modes of operation of switch mode power controller 20 have formed delay horizontal oscillator tube 86 idle a kind of means, with in picture drop-out when operational mode switches to standby mode and fluorescent screen anode voltage U discharge.During entering the transition interval of standby mode, the B+ voltage level of supplying with kickback transformer FBT disappears.But horizontal sweep and electron beam current in this transition period inside continue to keep, owing to+180V and+discharge of 24V power supply reduced amplitude, thereby the high-voltage anode voltage on the anode of fluorescent screen released.

The signal that produces in switch mode power is used to finish to enter the transition stage of standby mode.Because the voltage reference of switch mode power controller is different under operational mode and standby mode, high when operational mode, therefore, switch to the transition interval that standby mode follows later on from operational mode during, controller stops to produce exports pulse.When transition interval finished, controller produced pulse in " short pulse " mode, limits the end of this transition with this.Be this transition interval timing, the end that occurs limiting exactly again this transition interval again of pulse when transition finishes exactly in the difference on the reference level of controller 20 (higher than what under standby mode, provide) at the output voltage that provides under the operational mode.

In Fig. 3 to Fig. 7, after starting interval t0 to t1, controller 20 makes V _CCLevel remain between the upper and lower threshold value that is limited under " short pulse " mode, a series of risings between this two threshold value shown in Figure 3 and the ramp voltage of decline are provided whereby.Between standby period (t1-t2 constantly), controller 20 provides once in a while short pulse for power transformer LP36, as shown in Figure 5, and with V _CCRemain between two error input threshold values of controller 20.When the B+ supply voltage unloaded, it remained+the 118V (see figure 4).

Microprocessor 82 (for example because the signal effect in the infrared remote receiver (not shown) under) when t2 switches to operational mode constantly, STBY descends, and the P signal becomes+24V owing to transistor T R16 and TR17.So the P signal is to the V of horizontal oscillator tube 86 _CCSupplying power for input end will be coupled on the controller 20 by signal transformer LP42 from the duration-modulated pulse of pulse width modulator 92, so that synchronous with the flyback pulse from the signal VP of transformer FBT.Whereby, the feedback to controller 20 shifts to be coupled to the pulse-width modulated output signal of IS logical block 32 through transformer LP42 from the internal reference signal that is coupled to error amplifier 34.

The feedback of the duration-modulated pulse of being made up of through resistance R P51, RP52 and potentiometer PP52 modulator 92 that voltage divider carried out is based on B+ voltage, and is arranged to such an extent that B+ voltage is remained+118V.This causes the V of controller 20 _CCHave different and higher level, for example+13V.When the output of controller 20 influences all secondary winding W2-W5 of power transformer LP36, also regulate the V that comprises controller 20 by the adjusting of carrying out from the feedback of B+ voltage _CCLevel is at other interior secondary winding.Therefore, V under operational mode _CCBe conditioned approachingly+13V.Power supply by controller 20 and power transformer LP36 offer B+ ,+19V ,+24V and+the 5V power supply, and through transformer FBT offer deflection winding YH, fluorescent screen anode (high-voltage anode voltage U), kinescope driver 84 (+180V) and pulse width modulator 92 (+13V).Owing to load usually under operational mode, so controller 20 do not work in " short pulse " mode with normal mode, and at each horizontal scan period (Fig. 5) output duration-modulated pulse, with synchronous with the flyback pulse of signal UP (Fig. 6).

At t3 constantly, microprocessor 82 shifts and is standby mode, and allows signal STBY to become high level.Circuit begins to last till that from t3 t3 constantly from running to standby transition.At t3 constantly, response STBY signal (Fig. 7), signal P becomes low level immediately, because transistor T P69 no-bias, and the blocking-up pulse is through the feedback of signal transformer LP42 to controller 20.But, work on owing to storage voltage on capacitor CI21 makes horizontal oscillator tube 86, and diode DP05 blocking capacitor device CI21 discharges through transistor T P69.The V of horizontal oscillator tube 86 _CCVoltage begins to descend along with the discharge of capacitor CI21.

When the feedback to controller 20 did not exist, as at 13 o'clock constantly, controller 20 beginnings were regulated according to the input of error amplifier 34.Yet the input of this error is regulated between above-mentioned upper and lower two threshold values, it than when regulating the B+ voltages, kept by pulse width modulator 92+the 13V level is low.For this reason, controller 20 enters " short pulse " mode, and stops to produce the V that pulse obtains up to the winding W3 from power transformer LP36 _CCTill when being reduced to lower threshold value 10.45V (Fig. 3 and Fig. 5).

Between from the run transition to the standby period, the horizontal deflecting circuit continuous firing.And since diode DR10 no longer stop+the 5V level is coupled on the kinescope driver 84 by diode DR11, so, kinescope driver conducting and electron beam current is provided.Yet at t3 to t4 moment transition period, the B+ voltage that is loaded by deflection circuit and kinescope driver begins to descend, as shown in Figure 4.Be applied to the horizontal output voltage V of deflection circuit _HAlso descend.Along with the decline of the deflection current among the horizontal deflection winding YH, picture drop-out, and along with the discharge of fluorescent screen anode voltage U and supply with kinescope driver 84+180V voltage descends the image blackening.

The time delay of the transition state when entering standby mode is by being applied to operational mode V on the controller 20 _CCRegulate level to be about+13V and " short pulse " mode under the lower threshold value of controller 20 be about+difference of 10.45V limits, also by the V of capacitor CP28 by damping loads resistance R P21, Zener diode DP14 and controller 20 _CCThe discharge that input carries out limits.V under the operational mode _CCHigh level be set lowlyer than the voltage shutoff value of the maximum of controller 20, be 15.7V under the situation of TEA2260.In accordance with the embodiments illustrated, this transition state continues 121 milliseconds.

V at controller _CCWhen arriving lower threshold value, this transition stage finishes.Output at controller 20 sends pulse, and by transformer LP36 secondary winding W2 is coupled in this pulse, whereby, drives B+ voltage and turns back to its normal level+118V from its discharge level that is about 10V.Yet owing to horizontal oscillator tube is still worked when the discharge level of capacitor CI121, so the recovery of B+ voltage will recover deflection and the power supply that produces fluorescent screen anode and kinescope driver 84.The pulse that recovers to send on controller 20 outputs utilizes the input of X ray protection to integrated circuit IL01 in order in the output of turn-offing horizontal oscillator tube 86 forward, stops the output of horizontal oscillator tube 86.

Constantly controller 20 is again when the winding W1 of power transformer LP36 provides pulse at t4, and energy is coupled to secondary winding W4 and is applied on the signal XR by resistance R P87 and RV01.This signal, is driven XRP and is input on the integrated circuit IL01 by capacitor CV01 filtering by diode DV01 peak value rectification.Just drive by controller 20 at B+ voltage reset into+118V before, at t4 V constantly _HThe horizontal pulse at place is cut off exactly.

When horizontal deflection signal disappears, put owing to kinescope driver works on high pressure positive electricity to be pressed subtract, so the fluorescent screen anode discharges by electron beam current, reduced current potential to attendant's electric shock.The disappearance of image and the discharge of high-voltage anode voltage all by controller 20 exactly regularly, are exported with forward blocking horizontal oscillator tube when transition stage finishes.

Fig. 8 A illustrates the details of crt driver circuit 84 among Fig. 2 with the form of calcspar.Fig. 8 B illustrates the picture tube driving amplifier that uses among Fig. 8 A and the detailed circuit diagram of screen display (hereinafter referred to as " OSD ") driving amplifier.

In Fig. 8 A, " tuner---intermediate frequency (IF) amplifier---wave detector " unit 802 that has antenna input 804 is provided, change baseband form S2 in order to radio frequency (RF) input signal S1 with input 804 places.This baseband video signal S2 is applied on the video processing unit 806 of a routine, handle this signal and produce a luminance output signal Y and three color difference signal R-Y, B-Y and G-Y, these signals are applied on each negative electrode of picture tube 814 by picture tube driving amplifier 808,810 and 812 respectively.The high pressure of picture tube 814 (high-voltage anode current potential) is applied on the high-voltage anode terminal 816.

The mode of operation of microprocessor 82 receiver control of above discussing, and comprise a keyboard 83, in order to instruction to receiver input such as channel, ON/OFF, volume and relevant image controlled function.Microprocessor 82 also is provided at the function of the character of (OSD) generation RGB (red, green, orchid) form on the screen display.This osd signal is applied to tube cathode amplifier 808,810,812 through separately amplifier 820,822,824 to be had separately on the input.The OSD driving amplifier 824 that " green " drive signal is used also has another input 840 to be connected, in order to " operation/standby " signal that is provided by diode DR11 among Fig. 2 to be provided.

In operating process, tuner 802 and processor 806 produce the image of representation signal Y, R-Y, B-Y and G-Y, above-mentioned signal is by driving amplifier 808,810 and 812 matrixing and amplifications, is applied to then on R, G, the B " rifle " (being negative electrode) of picture tube 814.Microprocessor 82 produces RGB on the screen signal signal, be applied on each driving amplifier by amplifier 820,822 and 824 respectively.When the user utilizes keyboard 83 startings " shutoff receiver ", microprocessor 82 produces the power control signal of above describing, receiver is placed standby mode, and will be applied on " green " OSD driving amplifier 824 from " standby " signal of diode DR11.This just connects " green " negative electrode driving amplifier 812, makes " green " electron gun " generation " green " grating of picture tube whereby." green " rifle of picture tube has the ability to make the high-voltage anode voltage discharge when this grating disappears lentamente.Be under the complete situation from the transition that runs to shutoff, the high pressure of picture tube discharges fully, and no twilight sunset may take place, and during transition stage, because the grating that disappears has sizable area rather than concentrates on the point, therefore also can not produce the phenomenon that luminous point burns.

The schematic diagram of Fig. 8 B illustrates the operation that diode DR11 provided/standby " signal how to be applied to " green " OSD drive put on the device device and be applied to " green " negative electrode or " rifle " driving amplifier on details.Specifically, amplifier 824 comprises a NPN transistor 850, and its base stage is coupling on the input 890, in order to receive " operation/standby " signal from diode DR11.This base stage also is coupling on the input 842 through a resistance, in order to connecing " green " OSD drive signal (GREEN DRIVE), but also by " drop-down " resistance (make when the no base drive signal transistor 850 by) ground connection.The emitter of transistor 850 is by the emitter resistance ground connection than low resistance, and its collector coupled drives on the input 813 to " green " of amplifier 812.Small capacitor from the collector coupled of transistor 850 to ground, in order to the charge rate of restriction " green " osd signal, to avoid surpassing the bandwidth of picture tube and driving amplifier.

Driving amplifier 812 comprises a NPN transistor 860, and its base stage is coupled on the G-Y input 862 through a current-limiting resistance.The collector electrode of transistor 860 is coupled on the power supply terminal 864 through a load resistance, in order to receive high voltage source (about 180V); Also be coupled on the output 866 by an electrostatic discharge (ESD) protection resistance, this output is connected on " green " negative electrode of picture tube 814.The emitter circuit of transistor 860 comprises a variable gain controlling resistance and a shunt peaking capacitor that is coupled with luminance input 870.This emitter-coupled is to terminal 813, in order to receive " green " the OSD drive signal from amplifier 824; Also be coupled on the DC level regulating circuit, this regulating circuit comprises a potentiometer and a resistance, these two is coupled in series between a low-voltage source (about 9V) and the ground, and the delivery of this potentiometer is by the emitter-coupled of a current-limiting resistance and transistor 860.

Transistor 860 is in operating process, and to signal G-Y with Y makes up or matrixing, to produce the image of representative " green " output signal, this image is through amplifying on the after-applied green electron gun at picture tube.In order to obtain green output signal, the ratio of signal G-Y and Y is controlled by the variable emitter resistance of transistor 860.Whole DC level (brightness) is controlled by low pressure source potentiometer in the emitter circuit.When osd signal was produced by microprocessor 82, they were amplified after-applied on the emitter of " green " driving transistors 860 by transistor 850, and the negative electrode with picture tube 814 is driven on maximum " green " intensity level whereby.By driving the osd signal of all three rifles, then produce the OSD character of white.Can obtain the character of other color by the osd signal that drives R, G, B three rifles selectively.

Between the off period, " operation/standby " signal that is provided by diode DR11 makes transistor 850 conductings, produces " green " grating whereby.This makes any image representation signal surpass and drives that therefore along with raster size slowly reduces (above existing the explanation), green raster has uniform brightness.For this reason, the high-voltage anode voltage of picture tube discharge is avoided and twilight sunset can not take place thereby luminous point burns.

Notice that " during the transition region that carries out the transition to " standby " from " RUN " people can not dependency graph picture represent vision signal that the picture tube high voltage anode voltage is discharged " has benefit gained from others' wisdom.

The reason of " on behalf of vision signal, people can not the dependency graph picture make the high-voltage anode discharge " be image to represent vision signal be unpredictable, and the user make that receiver turns off instantaneous it be to be on the black level.

In view of the above, importantly realize benefit of the present invention, that is at least one rifle of this picture tube is switched on during transition region, so that the picture tube discharge.It is not reliable representing vision signal that this function is provided according to the frequency image.Certainly, though people can make the more than one rifle conducting of picture tube during grating disappears slowly,, have found that people need make the picture tube discharge by above-mentioned control mode.

Claims (1)

1. one kind has the television receiver that luminous point burns protection and twilight sunset inhibition facility, comprising: a picture tube; A driving amplifier is in order to drive above-mentioned picture tube; A high voltage source; A deflection circuit; A control circuit turn-offs command signal (" operation/standby ") in order to produce, and suspends to make this receiver during transition interval when operational mode becomes standby mode at this receiver; And above-mentioned high-voltage power supply is not worked and start the device that above-mentioned deflection circuit turn-offs with a kind of controlled speed in order to respond above-mentioned shutoff command signal;

Described receiver is characterized in that:

Above-mentioned driving amplifier comprises first (812) and second (824) amplifier;

Above-mentioned first amplifier (812) has: a signal input part (862; 870), in order to receive image representation signal (G-Y; Y); A control input end (813) is in order to receive control signal (G); And an output (866), be coupled on the electron gun of above-mentioned picture tube;

Above-mentioned first amplifier (812) response is applied to first level of the above-mentioned control signal (G) on the above-mentioned control input end (813), with so that be applied to above-mentioned signal input part (862; 870) the above-mentioned image representation signal (G-Y on; Y) any value blasting makes above-mentioned first amplifier (812) can make above-mentioned electron gun produce maximum output electron beam level;

Character signal (GREEN DRIVE) and above-mentioned shutoff command signal on above-mentioned second amplifier (824) the response screen display (operation/standby), this two signal is applied to first (GREEN DRIVE) of described second amplifier respectively) and second (840) input on, in order to produce above-mentioned first level of above-mentioned control signal (G);

The above-mentioned shutoff command signal of above-mentioned second amplifier (824) response (operation/standby), during above-mentioned transition interval, make character signal on the above-mentioned screen display device (GREEN DRIVE) blasting, so that above-mentioned control signal (G) presents above-mentioned first level, in above-mentioned first amplifier (812), make above-mentioned image representation signal (G-Y during the above-mentioned transition interval whereby, Y) blasting, to produce above-mentioned maximum output electron beam level, and carry out electrion from above-mentioned picture tube, and on above-mentioned picture tube, produce the demonstration of uniform luminance, to prevent above-mentioned image representation signal (G-Y across whole demonstration grating; Y) amplitude characteristic of character signal (GREEN DRIVE) unlikely luminous point that causes during above-mentioned transition interval burns and damages above-mentioned picture tube or on the screen display.

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