CN201577123U

CN201577123U - Circuit for eliminating shutdown bright spot of CRT display

Info

Publication number: CN201577123U
Application number: CN2009202606114U
Authority: CN
Inventors: 敬奕艳
Original assignee: Konka Group Co Ltd
Current assignee: Konka Group Co Ltd
Priority date: 2009-11-20
Filing date: 2009-11-20
Publication date: 2010-09-08
Anticipated expiration: 2019-11-20

Abstract

The utility model discloses a circuit for eliminating a shutdown bright spot of a CRT display. The circuit comprises a line sweep circuit, an oscillight, a red signal amplifying circuit, a green signal amplifying circuit, a blue signal amplifying circuit and a video decoding chip, wherein the red signal amplifying circuit, the green signal amplifying circuit and the blue signal amplifying circuit are used for respectively amplifying red, green and blue signals and sending the signals to a KR terminal, a KG terminal and a KB terminal of the oscillight connected with the circuits, the video decoding chip is used for decoding video signals, the red signals, the green signals and the blue signals are output from an R pin, a G pin and a B pin of the video decoding chip respectively, an HOUT pin outputs line drive signals to the line sweep circuit, an RGBVCC pin is connected with a drive power supply of the red signals, the green signals and the blue signals, and an HVCC pin is connected with a drive power supply of the line drive signals; and a control grid G1 of the oscillight is grounded. The utility model not only achieves the ideal effect of complete blank screen after the shutdown which is identical to cut-off bright spot elimination, but also decreases part of circuits, thereby lowering the material cost and the computer plug cost.

Description

A kind of circuit of eliminating the CRT monitor off-spot

Technical field

The utility model relates to display control circuit, relates in particular to a kind of circuit of eliminating the CRT monitor off-spot.

Background technology

Conventional picture tube (CRT) display is shutting down moment, can a bright spot occur in the screen center position usually, both cause picture tube to damage easily, also influences user's sense organ.For eliminating bright spot, the settling mode on the circuit mainly contains two kinds at present: by the bright mode and the bright mode that disappears of releasing of disappearing.

By disappearing bright mode: end the brightening circuit (referring to Fig. 4) that disappears external one of the control grid G1 of CRT, the negative voltage of hectovolt on producing one on the shutdown control grid G1 of moment at CRT, fast by electronics, prevent that electronics from getting on the fluorescent material, on screen, can not see light.Its major defect is: under the very low situation of present common CRT profit, just increased product cost owing to have by the brightening circuit that disappears.

The bright mode that disappears of releasing: at the KR of picture tube, KG, the KB end is outer to be respectively equipped with signal amplification circuit, and Fig. 1 is the danger signal amplifying circuit.After R, G, B tristimulus signals amplify by the pipe of the NPN in the signal amplification circuit respectively, insert the KR of picture tube respectively, KG, three negative electrodes of KB are controlled R respectively, G, three electron guns of B are got to the size of the electron stream on the corresponding fluorescent material on the phosphor screen.Cathode voltage is low more, and this electric current is big more, and screen is bright more; Otherwise electric current is more little, and screen is dark more.Make above-mentioned NPN manage rapid saturation conduction in the moment of shutting down, make picture tube KR, KG, three cathode voltages of KB are reduced to 0 level fast, produce the fluorescent material on the great beam electronic current impact fluorescence screen, the light of as seen dispersing on screen.Differentiation in the CRT manufacturing process causes the bright effect instability that disappears, and the CRT pipe of same model also usually needs to adjust different leadage circuit parameters and cooperates, and makes troubles for large batch of production; Be also shown in the light of dispersing on the shutdown moment screen, influence visual effect.

The utility model content

The utility model is the problems referred to above that will solve prior art, and it is low to propose a kind of cost, the circuit of the elimination CRT monitor off-spot that the photopic vision that disappears is effective.

For solving the problems of the technologies described above, the technical scheme that the utility model proposes is: a kind of circuit of eliminating the CRT monitor off-spot, comprise line-scan circuit, picture tube, respectively danger signal, green and blue signal are amplified and be delivered to danger signal amplifying circuit, green amplifying circuit and the blue signal amplifying circuit that connects picture tube KR, KG and KB end respectively, to the video decoding chip of vision signal decoding; The R of this video decoding chip, G and B pin be output red signal, green and blue signal respectively, the HOUT pin is to line-scan circuit output row energization signal, the RGBVCC pin inserts the driving power of danger signal, green and blue signal, and the HVCC pin inserts row energization signal driving power; The control grid G1 ground connection of above-mentioned picture tube.

The RGBVCC pin of above-mentioned video decoding chip can external first electric capacity, and the HVCC pin can external second electric capacity.The capacitance of first electric capacity is 10uf, and the capacitance of second electric capacity is 100uf.Video decoding chip can adopt the TDA11105 chip.

Compared with prior art, the utility model had both reached and the ideal effect that ends the equal complete blank screen of shutdown of bright mode that disappears, and had reduced a part of circuit again, had reduced material cost and plug in machine cost.

Description of drawings

Below in conjunction with drawings and Examples the utility model is made detailed explanation, wherein:

Fig. 1 is the danger signal amplifying circuit of prior art;

Fig. 2 is the utility model video decode control circuit;

Fig. 3 is the winding diagram of the utility model kinescope grid;

Fig. 4 is the brightening circuit that disappears that ends of prior art.

Embodiment

Referring to Fig. 2, the utility model comprises: line-scan circuit, picture tube, video decoding chip to the vision signal decoding, be serially connected in the danger signal amplifying circuit between video decoding chip R pin and the picture tube KR end, be serially connected in the green amplifying circuit between video decoding chip G pin and the picture tube KG end, be serially connected in the blue signal amplifying circuit between video decoding chip B pin and the picture tube KB end.Wherein video decoding chip R, G, B pin are distinguished output red signal, green and blue signal, the HOUT pin is to line-scan circuit output row energization signal, the RGBVCC pin inserts the driving power of danger signal, green and blue signal, and the HVCC pin inserts row energization signal driving power.Referring to Fig. 3, the control grid G1 ground connection of picture tube.

In preferred embodiment, external first capacitor C 6 of RGBVCC pin, external second capacitor C 5 of HVCC pin.And the capacitance of C6 is not more than 10uf, and the C5 capacitance is 100uf.Video decoding chip adopts the TDA11105 chip.

Below be example explanation circuit working principle with the danger signal, danger signal (R signal) is through behind the V1, obtain a voltage signal KR who oppositely amplifies, therefore when input R is 0 level, KR reaches its maximum, and at this moment the electric current of KR is 0, and promptly electron gun is not launched electronics, do not have the electron bombard red fluorescence powder, so screen can Show Color.Also is the same for green (G signal) with blue signal (B signal).

Switching off the TV machine moment, video decoding chip R, G, three signals of B are reduced to 0 level rapidly, and are stabilized in 0 level state, KR so, KG, three negative electrodes of KB just can stop to send electronics immediately.The row energization signal that video decoding chip sends still continues operate as normal a period of time, this time can be set at about 40ms, and this just can prevent that the electronics launched before this from getting to fluoroscopic center under the situation of magnetic deflection field and form off-spot losing.Because the limited amount of electronics is divergent state under the effect of magnetic deflection field, on screen, can form bright spot, and almost can't see yet light is arranged on the screen.Shutdown moment R, G, the speed that the B signal is reduced to 0 level depends on: the size of the capacitor C that connects 6 on a, the video decoding chip RGBVCC power supply pin; B, display circuit plate are to the load weight of RGBVCC power supply branch road; C, the inner R of decoding chip, G, B produce circuit to begin and out-of-work threshold voltage or electric current.Wherein a item and b item can design adjustment by circuit designer; In case just can't change and c item chip is fixing.The appearance value of C6 should not surpass 10uf, and the load of RGBVCC power supply branch road is lighter, helps improving R, G, B signal decrease speed.During shutdown, the speed that row energization signal HOUT disappears depends on: the size of the capacitor C that connects 5 on the HVCC power supply pin of d, decoding chip; E, display circuit plate are to the load weight of HVCC power supply branch road; F, the inner HOUT of decoding chip produce out-of-work threshold voltage of circuit or electric current.Wherein d and e item can be adjusted by circuit designer, in case and f item chip is fixing just can't change.For guaranteeing HOUT at R, G, B become tens milliseconds of working again after 0 level, about capacitor C 5 value 100uf.

Better embodiment of the present utility model has more than been described, but the those of skill in the art in the present technique field are to be understood that, these only illustrate, and can make numerous variations or modification to these execution modes, and not deviate from principle of the present utility model and essence.The scope that all belongs to the utility model protection.

Claims

1. circuit of eliminating the CRT monitor off-spot, comprise line-scan circuit, picture tube, respectively danger signal, green and blue signal are amplified and be delivered to danger signal amplifying circuit, green amplifying circuit and the blue signal amplifying circuit that connects picture tube KR, KG and KB end respectively, it is characterized in that also comprising: the video decoding chip of vision signal decoding; The R of this video decoding chip, G and B pin be output red signal, green and blue signal respectively, the HOUT pin is to line-scan circuit output row energization signal, the RGBVCC pin inserts the driving power of danger signal, green and blue signal, and the HVCC pin inserts row energization signal driving power; The control grid G1 ground connection of described picture tube.

2. the circuit of elimination CRT monitor off-spot as claimed in claim 1 is characterized in that: external first electric capacity of described RGBVCC pin (C6), external second electric capacity of described HVCC pin (C5).

3. the circuit of elimination CRT monitor off-spot as claimed in claim 2 is characterized in that: the capacitance of described first electric capacity (C6) is 10uf, and the capacitance of described second electric capacity (C5) is 100uf.

4. as the circuit of each described elimination CRT monitor off-spot of claim 1 to 3, it is characterized in that: described video decoding chip adopts the TDA11105 chip.