CN2772150Y - Colour television receiver starting-up image progressive-bright circuit - Google Patents

Abstract

The utility model discloses a color television receiver starting-up image progressive-bright circuit which comprises a CRT kinescope, wherein a red, a green and a blue cathodes R, G, B of the kinescope respectively receive red primary signals R, green primary signals G and blue primary signals B via respective video amplifying circuit. The primary signals can provide cathode voltage to the kinescope after the amplification of a triode transistor in the video amplifying circuits. The emitter of the transistor is connected with a starting-up controlling circuit which comprises a resistance-capacity charging circuit. With making use of the charging current characteristic of gradual small in starting-up, the resistance-capacity charging circuit changes the voltage difference between the emitter and a base of the crystal transistor in the video amplifying circuit so as to control the collector output voltage of the transistor to be gradual large, therefore television images are gradually bright from dark until normal view. The utility model has the advantage of simple structure and effectively solves the problem of streaking in the starting-up, and meanwhile, the utility model reduces visual impact generated from rapid shown images.

Description

Color television set start image progressive-bright circuit

Technical field

The utility model relates to a kind of improvement of TV set circuit, and specifically, relating to a kind of being used for the picture tube is the TV of display, the gradually bright circuit of image when realizing its start.

Background technology

For the color television set that uses picture tube as display device, display image need be used the filament heated cathode, and the voltage that needs negative electrode, intensifying ring, high-voltage anode is on suitable value.During start just, filament has just obtained voltage, need certain hour just can reach the temperature of appointment, but intensifying ring, high-voltage anode are only to rely on voltage power supply, so this moment, picture tube was in abnormal operating state, the part that brightness ratio in the image is higher or color saturation is bigger, actual displayed are come out is the obvious tail of a segment length in tow to the right, and Here it is ordinary color tv set is at the just tailing problem of ten seconds left and right sides time of start.At present, there are a lot of methods can solve the start tailing problem, for example improve the cathode voltage of picture tube, can reduce the emissivities of negative electrode like this; Perhaps improve intensifying ring voltage, increase the emission rate of electronics.Because this way not only works when start just, watching in the process after start still worked, and be lighter thereby integral image becomes, and influenced the effect of watching of image.Even so will adopt such scheme, also will take into account image effect and inhibition situation, can not reach the purpose of thorough elimination.

Summary of the invention

The utility model provides a kind of television boot-strap image progressive-bright circuit in order to overcome the problem of television set appearance hangover when starting shooting in the prior art, and this circuit is controlled tube cathode voltage and is in than higher state the elimination hangover when start just; After start process was finished, the tube cathode temperature reached designated value, and the cathode voltage that recovers picture tube is to normal degree, thus assurance clear picture, bright-coloured.

For solving the problems of the technologies described above, the utility model is achieved by the following technical programs:

A kind of color television set start image progressive-bright circuit, comprise the CRT picture tube, the red, green, blue negative electrode R of described picture tube, G, B receive red primary signal R, green primary signal G and blue primary signal B through separately video amplifier circuit respectively, provide cathode voltage for picture tube after the transistor of described primary colour signal in video amplifier circuit amplifies; Emitter at described triode is connected with a start control circuit, in described start control circuit, DC power supply is through electric capacity and grounding through resistance, described electric capacity and resistance series connection, its tie point links to each other with the base stage of a P type triode, the collector electrode of described P type triode links to each other with the base stage of a N type triode, the grounded emitter of described N type triode, collector electrode connects the emitter of described P type triode on the one hand, and link to each other with DC power supply by resistance, link to each other with the emitter of transistor in the described video amplifier circuit on the other hand.

As to further qualification of the present utility model, described video amplifier circuit includes two transistors, wherein, the base stage of first triode links to each other with DC power supply, collector electrode connects the negative electrode of picture tube on the one hand, link to each other with a power supply through a resistance on the other hand, its emitter links to each other with the collector electrode of described second triode; The base stage of described second triode receives primary colour signal, emitter resistance grounded.

As further limiting of the present utility model, the voltage of described DC power supply is 9V or 12V again; The voltage of power supply at 180V between the 250V.

Compared with prior art, advantage of the present utility model and good effect are: the utility model is by setting up the start control circuit that includes rc charging circuit, charging current characteristics from large to small when utilizing start, change the base stage of transistor in the video amplifier circuit and the voltage difference between the emitter, and then the collector electrode output voltage of control triode changes from small to big, make TV images by secretly brightening, up to normal demonstration.This circuit structure is simple, and the streaking problem when efficiently solving start has reduced the visual impact that the quick appearance of image is produced simultaneously.

Description of drawings

Fig. 1 is the gradually concrete circuit connection diagram of bright control circuit of the utility model television boot-strap image.

Embodiment

Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.

The purpose of start smearer of the present utility model is the cathode voltage of control picture tube, and the cathode voltage of picture tube depends on the output of video amplifier circuit, for common video amplifier circuit, the collector electrode that normally utilizes transistor is as output.The collector electrode output voltage that is in the triode of magnifying state depends on the pressure reduction between base stage and the emitter, and the utility model utilizes this pressure reduction to come work.

Among Fig. 1, R, G, B video amplifier circuit receive primary colour signal R, G, B separately respectively, with the R video amplifier circuit is example, red primary signal R is connected to the base stage of N type triode VT2 through resistance R 1, through resistance R 4 or resistance R 3, capacitor C 1 ground connection, collector electrode links to each other with the emitter of another N type triode VT1 its emitter respectively.The base stage of described triode VT1 links to each other with a direct current power supply VCC2, and collector electrode one tunnel links to each other with power supply VCC1 through resistance R 5, and another road is connected to the R negative electrode of picture tube CRT, for it provides cathode voltage.In addition, the emitter of described N type triode VT2 also links to each other with a start control circuit, in described start control circuit, DC power supply VCC2 is through capacitor C 10 and resistance R 10 ground connection, described capacitor C 10 and resistance R 10 series connection, its tie point links to each other with the base stage of P type triode VT11, the collector electrode of described P type triode VT11 links to each other with the base stage of a N type triode VT10, the grounded emitter of described N type triode VT10, collector electrode connects the emitter of described P type triode VT11 on the one hand, and link to each other with DC power supply VCC2 by resistance R 12, the emitter of the transistor VT2 in resistance R 2 and described video amplifier circuit links to each other on the other hand.Wherein, the voltage of described DC power supply VCC2 is 9V or 12V, the voltage of power supply VCC1 at 180V between the 250V.

During start just, DC power supply VCC2 grows out of nothing, and the charging current that produces capacitor C 10 flows through resistance R 10 formation loops.Charging current flows through resistance R 10 and produces pressure drop, the conducting size of control P type triode VT11.When the charging current of capacitor C 10 was big, triode VT11 conducting was little, and then made triode VT10 conducting also little, and this moment, the electric current by resistance R 12 was just smaller, and the pressure drop of generation is lower, thereby the collector voltage that makes triode VT10 is than higher.This voltage passes to the emitter of triode VT2 by resistance R 2, makes the base stage of triode VT2 and the pressure reduction between the emitter less, and the ducting capacity of triode VT2 is also less, and the electric current of collector electrode is corresponding to be reduced.Because the emitter of triode VT1 directly is connected on the collector electrode of triode VT2, so the base current of triode VT1 is also little, collector current also diminishes.Power supply VCC1 is connected to the collector electrode of triode VT1 by resistance R 5, less current makes the pressure drop on the resistance R 5 less, so the collector voltage of triode VT1 is higher, this voltage is connected to the R negative electrode of picture tube CRT by resistance, and red is luminous just more weak.In like manner, G, B video amplifier circuit also are controlled by said process, and be luminous also more weak, and corresponding entire image is just relatively darker, just do not see on the screen even at all shinny, thereby the tailing problem when having solved television startup.

Therefore the charging current on the capacitor C 10 directly determines the voltage of tube cathode, directly controls the brightness of screen picture.After the start, the charging current on the capacitor C 10 is along with the prolongation of time reduces gradually, and the cathode voltage of picture tube just reduces gradually, and it is more and more brighter that screen picture becomes.When the charging current of capacitor C 10 was reduced to a certain degree, the cathode voltage of picture tube just was not subjected to the control of capacitor C 10 grades basically, display image normally, thus effectively reduced the image visual impact that produced of appearance fast.Suitably adjust the value of capacitor C 10 and resistance R 10, just can control the gradually bright time of start,, need the time in 10 seconds approximately according to the parameter on the accompanying drawing 1.

Certainly; above-mentioned explanation is not to be to restriction of the present utility model; the utility model also is not limited in above-mentioned giving an example, and variation, remodeling, interpolation or replacement that those skilled in the art are made in essential scope of the present utility model also should belong to protection range of the present utility model.

Claims (4)

1. color television set start image progressive-bright circuit, comprise the CRT picture tube, the red, green, blue negative electrode R of described picture tube, G, B receive red primary signal R, green primary signal G and blue primary signal B through separately video amplifier circuit respectively, provide cathode voltage for picture tube after the transistor (VT1, VT2) of described primary colour signal in video amplifier circuit amplifies; It is characterized in that: the emitter at described triode (VT2) is connected with a start control circuit, in described start control circuit, DC power supply (VCC2) is through electric capacity (C10) and resistance (R10) ground connection, described electric capacity (C10) and resistance (R10) series connection, its tie point links to each other with the base stage of a P type triode (VT11), the collector electrode of described P type triode (VT11) links to each other with the base stage of a N type triode (VT10), the grounded emitter of N type triode (VT10), collector electrode connects the emitter of described P type triode (VT11) on the one hand, and link to each other with DC power supply (VCC2) by resistance (R12), link to each other with the emitter of transistor (VT2) in the described video amplifier circuit on the other hand.

2. color television set start image progressive-bright circuit according to claim 1, it is characterized in that: described video amplifier circuit includes two transistors (VT1, VT2), wherein, the base stage of first triode (VT1) links to each other with DC power supply (VCC2), collector electrode connects the negative electrode of picture tube on the one hand, link to each other with a power supply (VCC1) through a resistance (R5) on the other hand, its emitter links to each other with the collector electrode of described second triode (VT2); The base stage of described second triode (VT2) receives primary colour signal, and emitter is through resistance (R4) ground connection.

3. color television set start image progressive-bright circuit according to claim 1 and 2, it is characterized in that: the voltage of described DC power supply (VCC2) is 9V.4. color television set start image progressive-bright circuit according to claim 1 and 2, it is characterized in that: the voltage of described DC power supply (VCC2) is 12V.

5. color television set according to claim 2 start image progressive-bright circuit is characterized in that: the voltage of described power supply (VCC1) at 180V between the 250V.

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