CN101399908B - Circuit for automatically regulating amplitude of video output signal of television - Google Patents
Circuit for automatically regulating amplitude of video output signal of television Download PDFInfo
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- CN101399908B CN101399908B CN2008102168270A CN200810216827A CN101399908B CN 101399908 B CN101399908 B CN 101399908B CN 2008102168270 A CN2008102168270 A CN 2008102168270A CN 200810216827 A CN200810216827 A CN 200810216827A CN 101399908 B CN101399908 B CN 101399908B
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Abstract
The invention discloses a circuit which automatically adjusts the video output signal amplitude of a TV. The circuit includes an image processing chip, a controllable gain amplification circuit which connects the image processing chip of the TV for receiving a video signal output by the image processing chip of the TV, amplifying and automatically adjusting the video output signal amplitude of the TV; a voltage generating circuit for generating a voltage which is positively increasing with the amplitude of a synchronous signal in the video output signal of the TV and is based on the synchronous signal as well as a voltage comparing amplifying circuit and a lowpass filter circuit; wherein, the voltage comparing amplifying circuit generates a difference voltage according to the comparison between the voltage generated by the voltage generating circuit based on the synchronous signal and a benchmark voltage; after passing through the lowpass filter circuit, the gain of the controllable gain amplification circuit is adjusted, thereby being capable of automatically adjusting and regulating the output signal amplitude of the TV.
Description
[technical field]
The present invention relates to technical field of television sets, particularly a kind of circuit of automatic adjusting amplitude of video output signal of television.
[background technology]
Development along with television technologies, and the consumer is more and more higher to the television function requirement, and television set has been not only TV reception, and its function is more and more, corresponding its interface of various function is also more and more abundanter, video output having become one of indivisible pith of television set.Television video output at present is mostly after process chip output, only adds a buffering or an amplifying element and handles.Therefore certainly exist following problem: 1) because the process chip variation of output signals, the amplitude of video output signals is on the low side or higher; 2) because the variation of load, the amplitude of video output signals is on the low side or higher.Signal is on the low side to cause that image effect is poor, signal to noise ratio reduces even problems such as image is asynchronous occur, causes problems such as image deflects, visual level are few and signal is higher.Therefore, be necessary that research provides solution of the above problems,, improve the image quality of video output signals with the stable video output signal.
[summary of the invention]
For addressing the above problem, main purpose of the present invention is to provide a kind of circuit of automatic adjusting amplitude of video output signal of television.
For achieving the above object, technical scheme of the present invention is: a kind of circuit of automatic adjusting amplitude of video output signal of television, include picture processing chip, connect picture processing chip to receive the vision signal of its output, amplify and regulate the controllable gain amplifying circuit of amplitude of video output signal of television automatically, according to the synchronizing signal in the described video output signals of television, produce voltage generation circuit and voltage contrasting amplified circuit and the low-pass filter circuit that become the voltage of positive increase with described synchronizing signal amplitude based on synchronizing signal; Wherein, described voltage contrasting amplified circuit produces difference voltage according to the voltage and the comparison of reference voltage that described voltage generation circuit based on synchronizing signal produces, pass through low-pass filter circuit after, regulate the gain of described controllable gain amplifying circuit.
Compared to prior art, the circuit that the present invention regulates amplitude of video output signal automatically is made of controllable gain amplifying circuit, the voltage generation circuit based on synchronizing signal, voltage contrasting amplified circuit, low-pass filter circuit, can regulate the amplitude with stable television machine outputting video signal automatically.
[description of drawings]
Fig. 1 regulates the theory diagram of the circuit of amplitude of video output signal of television automatically for the present invention.
Fig. 2 regulates the schematic diagram of the circuit of amplitude of video output signal of television automatically for the present invention.
Fig. 3 is the theory diagram based on the voltage generation circuit of synchronizing signal shown in Fig. 2.
Fig. 4 is the theory diagram of the controllable gain amplifying circuit shown in Fig. 2.
[embodiment]
See also Fig. 1, shown in Figure 2, the circuit of a kind of automatic adjusting amplitude of video output signal of television of the present invention, comprise picture processing chip, connect the vision signal that picture processing chip receives its output, amplify and regulate the controllable gain amplifying circuit of amplitude of video output signal of television automatically, according to the synchronizing signal in the described video output signals of television, produce voltage generation circuit and voltage contrasting amplified circuit and the low-pass filter circuit that become the voltage of positive increase with described synchronizing signal amplitude based on synchronizing signal.Described voltage contrasting amplified circuit, the voltage that produces according to described voltage generation circuit based on synchronizing signal and the comparison of reference voltage, produce difference voltage, this difference voltage is used to regulate the gain of described controllable gain amplifying circuit through behind the low-pass filter circuit.
Through after the amplification of controllable gain amplifying circuit, export the vision signal Uo after amplifying behind the vision signal Ui of the image processing ics output on the TV SKD, this signal will directly be exported by the video output terminal on the television set.By detecting the synchronizing signal amplitude of outputting video signal Uo, produce direct voltage Ua based on the voltage generation circuit of synchronizing signal.Direct voltage Ua and reference voltage Uref compare and enlarge, and the difference voltage Ue of generation goes to control the gain of ride gain amplifying circuit, thereby regulates the amplitude of video output signals Uo automatically through becoming control voltage U c after the low-pass filtering.
Please refer to Fig. 2 to shown in Figure 4, the controllable gain amplifying circuit is made up of amplifying element and negative feedback links, and negative feedback links is made up of resistance R _ f and thyrite Rc, degeneration factor F=Rc/ (Rc+Rf).Control voltage U c increases, and thyrite Rc reduces, and feedback factor reduces, and then the gain of controllable gain amplifying circuit increases; Control voltage U c reduces, and thyrite Rc increases, and feedback factor increases, and then the gain of controllable gain amplifying circuit reduces.
Voltage generation circuit based on synchronizing signal is made up of separated in synchronization amplifying circuit, isolated DC, rectification circuit and the circuit of averaging.Behind isolated synchronizing signal process isolated DC, the rectification circuit of synchronizing separator circuit and the circuit of averaging, the DC level of the mean value Ua of output is (t1*h1+t2*h2)/(t1+t2), wherein (h1+h2), (t1+t2) are respectively synchronizing signal amplitude, the line period after the amplification, t1*h1=t2*h2.As seen Ua becomes positive increase (perhaps direct ratio) relation with synchronizing signal amplitude, and promptly the synchronizing signal amplitude of Uo increases, and Ua increases, and promptly the synchronizing signal amplitude of Uo reduces, and Ua reduces.
The reference data voltage U ref of voltage contrasting amplified circuit is connected to the in-phase input end of voltage contrasting amplified circuit, the Ua value that its synchronizing signal amplitude that is equivalent to video output signals Uo is exported during for standard value is (when the synchronizing signal amplitude of Uo is standard value, Uo=Uref).Ua and Uref compare and enlarge back output error voltage Ue.Wherein, there are following relation in Ua, Uref and Ue:
Ua〉Uref, difference voltage Ue＜0;
Ua＜Uref, difference voltage Ue〉0;
Ua=Uref, difference voltage Ue=0.
Difference voltage goes to adjust the parameter of controllable gain amplifier through becoming control voltage U c after the low-pass filtering, regulates its gain, thus the amplitude of regulating video output signals Uo automatically, with the stable video output signal.
Wherein, as outputting video signal Uo amplitude overgauge amplitude, then Ua〉Uref, difference voltage Ue and control voltage U c will reduce the gain of controllable gain amplifying circuit less than 0, and the amplitude of regulating outputting video signal Uo automatically is until being standard value; When outputting video signal Uo amplitude less than the standard amplitude, Ua＜Uref then, difference voltage Ue and control voltage U c are greater than 0, with the gain of rising controllable gain amplifying circuit, the amplitude of regulating outputting video signal Uo automatically is until being standard value; When outputting video signal Uo amplitude is the standard amplitude, Ua=Uref then, difference voltage Ue and control voltage U c are 0, do not need to regulate the gain of controllable gain amplifying circuit, it is constant that outputting video signal Uo amplitude is maintained standard value.
Most preferred embodiment described above only is that the present invention is set forth and illustrates, but is not limited to disclosed any concrete form, and it is possible carrying out many modifications and variations.
Claims (5)
1. circuit of automatically regulating amplitude of video output signal of television, include picture processing chip, it is characterized in that: also include the connection picture processing chip to receive the vision signal of its output, amplify and regulate the controllable gain amplifying circuit of amplitude of video output signal of television automatically, according to the synchronizing signal in the described video output signals of television, produce voltage generation circuit and voltage contrasting amplified circuit and the low-pass filter circuit that become the voltage of positive increase with described synchronizing signal amplitude based on synchronizing signal; Wherein, described voltage generation circuit based on synchronizing signal includes separated in synchronization amplifying circuit, isolated DC, rectification circuit and the circuit of averaging; Wherein, behind isolated synchronizing signal process isolated DC, the rectification circuit of separated in synchronization amplifying circuit and the circuit of averaging, output DC is flat, produces direct voltage; Described voltage contrasting amplified circuit produces difference voltage according to the direct voltage and the comparison of reference voltage that described voltage generation circuit based on synchronizing signal produces, pass through low-pass filter circuit after, regulate the gain of described controllable gain amplifying circuit.
2. the circuit of automatic adjusting amplitude of video output signal of television as claimed in claim 1 is characterized in that: described controllable gain amplifying circuit includes amplifying element and negative feedback links.
3. the circuit of automatic adjusting amplitude of video output signal of television as claimed in claim 2 is characterized in that: described negative feedback links is made up of resistance (Rf) and thyrite (Rc).
4. the circuit of automatic adjusting amplitude of video output signal of television as claimed in claim 3 is characterized in that: described reference voltage is connected to the in-phase input end of voltage contrasting amplified circuit.
5. the circuit of automatic adjusting amplitude of video output signal of television as claimed in claim 4 is characterized in that: the output of described voltage contrasting amplified circuit is connected to low-pass filter circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008102168270A CN101399908B (en) | 2008-10-13 | 2008-10-13 | Circuit for automatically regulating amplitude of video output signal of television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008102168270A CN101399908B (en) | 2008-10-13 | 2008-10-13 | Circuit for automatically regulating amplitude of video output signal of television |
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| Publication Number | Publication Date |
|---|---|
| CN101399908A CN101399908A (en) | 2009-04-01 |
| CN101399908B true CN101399908B (en) | 2010-08-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2008102168270A Active CN101399908B (en) | 2008-10-13 | 2008-10-13 | Circuit for automatically regulating amplitude of video output signal of television |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103762953B (en) * | 2014-01-16 | 2016-05-04 | 四川和芯微电子股份有限公司 | Automatic gain adjusting circuit |
| CN103761964B (en) * | 2014-01-16 | 2016-04-13 | 四川和芯微电子股份有限公司 | Automatic speech recognition circuit |
| KR102083233B1 (en) | 2016-10-25 | 2020-03-02 | 선전 구딕스 테크놀로지 컴퍼니, 리미티드 | Amplitude limited oscillation circuit |
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