CN106060436A - Video output method, video output circuit and multimedia terminal - Google Patents
Video output method, video output circuit and multimedia terminal Download PDFInfo
- Publication number
- CN106060436A CN106060436A CN201610184634.6A CN201610184634A CN106060436A CN 106060436 A CN106060436 A CN 106060436A CN 201610184634 A CN201610184634 A CN 201610184634A CN 106060436 A CN106060436 A CN 106060436A
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- Prior art keywords
- video
- video output
- level shifter
- diode
- port
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/445—Receiver circuitry for the reception of television signals according to analogue transmission standards for displaying additional information
- H04N5/44504—Circuit details of the additional information generator, e.g. details of the character or graphics signal generator, overlay mixing circuits
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- Engineering & Computer Science (AREA)
- Computer Graphics (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Picture Signal Circuits (AREA)
Abstract
The invention relates to the technical field of electronics, and discloses a video output method, a video output circuit and a multimedia terminal. In the invention, the video output circuit comprises a power supply, a level transfer module and a diode, and is characterized in that a first port of the level transfer module is connected with an output end of a video chip, a second port of the level transfer module is connected with a positive electrode of the power supply, a third port of the level transfer module is connected with a positive electrode of the diode, and a fourth port of the level transfer module is grounded; a negative electrode of the diode is connected with a video output terminal; and a negative electrode of the power supply is grounded. Voltage backward flow caused by insertion of other input lines is prevented by using the diode, and the video chip is protected. Meanwhile, the diode has forward voltage drop when being conducted, and a first voltage signal outputted by the video chip is elevated by using the level transfer module so as to compensate the forward voltage drop of the diode, so that the first voltage signal is prevented from being clipped, and normal output of the first voltage signal is ensured. The video output circuit is simple in structure, easy to implement and low in cost.
Description
Technical field
The present invention relates to electronic technology field, particularly to a kind of picture output method, circuit and multimedia terminal.
Background technology
Along with the fast development of science and technology, the continuous lifting of video definition, increasing television product sets
There is video output circuit.User can use video signal cable television set and other display equipment to be attached, after connection just
Can be on the first voltage signal synchronism output of television set to another display device.Current mode video output circuit can lead to
Cross non-essential resistance and reach to adjust the purpose of the amplitude of output voltage, and video chip also is able to drive electric current to reach by adjustment
Adjust the amplitude purpose of output voltage.
In realizing process of the present invention, inventor finds that in prior art, at least there are the following problems: as it is shown in figure 1, be
The circuit diagram of the first video output circuit of the prior art.One end of resistance R0 and electric capacity C0 is respectively with earth terminal GND even
Connecing, the other end is connected with video output terminal a, and the VT mouth of video chip 1 is connected with video output terminal a.
When video signal cable is inserted into video output terminal a by user, the transmission of signal can be realized.But, regarding on television set
Frequently the outward appearance of the signaling interface such as terminal, audio terminal is the most similar, and user is in the case of careless, it is easy to input a signal into
Line is mistakenly inserted in the video output terminal a being connected with video chip 1, if external circuit output voltage is too high, is loaded directly into
On video chip, easily cause the situation that video chip damages.
As in figure 2 it is shown, be the circuit diagram of the second video output circuit of the prior art.This circuit can effectively be prevented
The situation that the voltage that only insertion of other signal input line is caused pours in down a chimney.In fig. 2, the electric current that video chip 1 is exported
Need to first pass through resistance R6 and resistance R7 and carry out voltage lifting.But, the lifting of voltage can cause the electricity that video chip 1 exports
Pressure signal attenuation, therefore needs in subsequent conditioning circuit with two audion Q2, Q3, resistance R3, R4, R5, R8, R9, electric capacity C2, power supply
The circuit of V composition carries out signal amplification, and the video signal transmission after amplifying is to video output terminal a, guarantee video core
The voltage signal of sheet 1 output normally exports, but, this circuit structure is complicated, relatively costly.
Summary of the invention
A kind of picture output method of offer, circuit and multimedia terminal are provided, effectively prevent
Other input line inserts the situation that the voltage caused pours in down a chimney, it is achieved that protection to video chip, and circuit structure letter
Single, easily realize, low cost.
For solving above-mentioned technical problem, embodiments of the present invention provide a kind of video output circuit, are connected to video
Between outfan and the video output terminal of chip；Wherein, video output circuit comprises: power supply, Level shifter module and two poles
Pipe；
First port of Level shifter module is connected with the outfan of video chip, the second port of Level shifter module with
The positive pole of power supply connects, and the 3rd port of Level shifter module is connected with the positive pole of diode, the 4th end of Level shifter module
Mouth ground connection；The negative pole of diode is connected with video output terminal；The minus earth of power supply；
After the first voltage signal that video chip is exported by Level shifter module promotes, defeated to video by diode output
Go out terminal；Wherein, Level shifter module is equal to the forward voltage drop value on diode to the lifting values of the first voltage signal.
Embodiments of the present invention additionally provide a kind of multimedia terminal, comprise: above-mentioned video output circuit.
Embodiments of the present invention additionally provide a kind of picture output method, are applied to above-mentioned video output circuit, should
The first voltage signal that picture output method comprises the steps of video chip exports promotes；After voltage increase
First voltage signal exports to video output terminal through diode；Wherein, the lifting values of the first voltage signal is equal on diode
Forward voltage drop value.
In terms of existing technologies, video output circuit only comprises embodiment of the present invention: power supply, level transfer mould
Block and diode.Video output circuit is connected between the outfan of video chip and video output terminal.Level shifter module
The first port be connected with the outfan of video chip, the second port of Level shifter module is connected with the positive pole of power supply, level
3rd port of shift module is connected with the positive pole of diode, the 4th port ground connection of Level shifter module；The negative pole of diode
It is connected with video output terminal；The minus earth of power supply.Utilize diode that other the insertion of input line can be stoped to be caused
Voltage pour in down a chimney, it is achieved the protection to video chip, simultaneously as there is forward voltage drop during diode current flow, first with level
The first voltage signal that video chip is exported by shift module promotes, and in order to compensate the pressure drop on diode, thus avoids
The first voltage signal clipped wave, it is ensured that the normal output of the first voltage signal；Wherein, Level shifter module is to the first voltage
The lifting values of signal is equal to the forward voltage drop value on diode.
It addition, Level shifter module comprises the first resistance R1 and audion Q1.The base stage of Q1 is the of Level shifter module
Single port；One end of R1 is the second port of Level shifter module, and the other end is connected with the emitter stage of Q1, and the transmitting of Q1 is the most electric
3rd port of flat shift module；4th port of the most described Level shifter module of current collection of described Q1.Utilize audion Q1
The first voltage signal exported by video chip with resistance R1 promotes, to ensure that the level magnitudes of video output circuit will not
Clipped wave, it is ensured that the normal output of the first voltage signal.And, circuit is simple, it is easy to accomplish, low cost.
It addition, video output circuit also comprises filtration module.Filtration module one end is connected with the positive pole of power supply, another termination
Ground, can filter out interference signal so that the video signal of video output circuit output is purer.
It addition, video output circuit also comprises current/voltage modular converter.One end of current/voltage modular converter and video
The outfan of chip connects, other end ground connection；Current/voltage modular converter is by the electric current of current mode video frequency output in video chip
Signal is converted into the first voltage signal.Utilize current/voltage modular converter can take out the electricity that the current source of video chip exports
Pressure, it is ensured that the feasibility of embodiment of the present invention.
Accompanying drawing explanation
Fig. 1 is the circuit diagram according to video output circuit of the prior art；
Fig. 2 is the circuit diagram according to video output circuit of the prior art；
Fig. 3 is the circuit diagram according to the video output circuit in first embodiment of the invention；
Fig. 4 is the circuit diagram according to the video output circuit in first embodiment of the invention；
Fig. 5 is the level waveforms figure according to the video chip outfan in first embodiment of the invention；
Fig. 6 is the flow chart according to a kind of picture output method in third embodiment of the invention.
Detailed description of the invention
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with the accompanying drawing each reality to the present invention
The mode of executing is explained in detail.But, it will be understood by those skilled in the art that in each embodiment of the present invention,
In order to make reader be more fully understood that, the application proposes many ins and outs.But, even if there is no these ins and outs and base
Many variations and amendment in following embodiment, it is also possible to realize the application each claim technical side required for protection
Case.
First embodiment of the present invention relates to a kind of video output circuit.With reference to shown in Fig. 3, video output circuit connects
Between the Ausgang and video output terminal a of video chip 1.Video output circuit comprises: power supply V, Level shifter module 2
With diode D1.
Physical circuit is: the first port b of Level shifter module 2 is connected with the Ausgang of video chip 1, and level shifts
The positive pole of the second port c and the power supply V of module 2 is connected, and the positive pole of the 3rd port d and diode D1 of Level shifter module 2 is even
Connect, the 4th port e ground connection of Level shifter module 2.The negative pole of diode D1 is connected with video output terminal a.The negative pole of power supply V
Ground connection.
Wherein, Level shifter module 2 comprises the first resistance R1 and audion Q1, as shown in Figure 4.The base stage of audion Q1 is
First port b of Level shifter module 2, the 3rd port d, audion Q1 of the transmitting of audion Q1 extremely Level shifter module 2
The 4th port e of current collection extremely Level shifter module 2.Second port that one end is Level shifter module 2 of the first resistance R1
C, the other end is connected with the emitter stage of audion Q1.Utilize the first voltage letter that video chip is exported by audion Q1 and resistance R1
Number promote, in order to compensate forward voltage drop during diode D1 conducting, to avoid the first voltage signal clipped wave, it is ensured that the
The normal output of one voltage signal.Wherein, audion Q1 is equal to the forward on diode D1 to the lifting values of the first voltage signal
Voltage drop value.
Specifically, the voltage utilizing diode D1 that other the insertion of input line can be stoped to be caused pours in down a chimney, it is achieved
Protection to video chip, simultaneously as there is forward voltage drop during diode D1 conducting, will regard first with Level shifter module 2
First voltage signal of chip 1 output frequently promotes, and in order to compensate the pressure drop on diode D1, thus avoids the first voltage
Signal clipped wave, it is ensured that the normal output of the first voltage signal.
In present embodiment, video output circuit also comprises current/voltage modular converter.The one of current/voltage modular converter
End is connected with the Ausgang of video chip 1, other end ground connection.Current/voltage modular converter is by current mode video in video chip
The current signal of output is converted into the first voltage signal.Utilize current/voltage modular converter can take out the current source of video chip
The voltage of output, to ensure the feasibility of embodiment of the present invention.In present embodiment, current/voltage modular converter comprises
Two resistance R2.Second resistance R2 one end is connected with the outfan of video chip 1, other end ground connection.
Hereinafter the operation principle of video output circuit is illustrated: the second resistance R2 takes out the electricity of video chip 1
The voltage of stream source output, the synchronous head level of this output voltage is 0.8V, and white level amplitude is 1.8V, video chip 1 Ausgang
Level waveforms as shown in Figure 5.In video output circuit, the circuit at audion Q1 place has higher input impedance, from
Without have influence on that base stage receives
The wave-shape amplitude of one voltage signal so that the wave-shape amplitude of the first voltage signal is constant.Further, audion Q1's is defeated
Going out impedance relatively low, carrying load ability is strong, by the first voltage signal integral raising 0.6V.Diode D1 is overall by the first voltage signal
Decline 0.6V, thus ensure that the first voltage signal exports with normal size, and diode D1 can play and stop other
The effect that the voltage that the insertion of input line is caused pours in down a chimney, it is achieved thereby that the protection to video chip 1.
It is noted that in present embodiment, video output circuit also comprises filtration module, filtration module one end and electricity
The positive pole of source V connects, other end ground connection so that the video signal of video output circuit output is purer, such that it is able to will interference
Signal filters out.In present embodiment, filtration module comprises electric capacity C1, electric capacity C1 one end and is connected with the positive pole of power supply, the other end
Ground connection.
Second embodiment of the present invention relates to a kind of multimedia terminal, comprises the video frequency output electricity in the first embodiment
Road.
Third embodiment of the present invention relates to a kind of picture output method, and idiographic flow is as shown in Figure 6.It is applied to first
Video output circuit in embodiment, step is as follows:
Step 301, promotes the first voltage signal that video chip exports.
Step 302, exports the first voltage signal after voltage increase to video output terminal through diode.Wherein,
The lifting values of one voltage signal is equal to the forward voltage drop value on diode.
Specifically, the voltage utilizing diode that other the insertion of input line can be stoped to be caused pours in down a chimney, it is achieved right
, simultaneously as there is forward voltage drop during diode current flow, first with Level shifter module by video chip in the protection of video chip
First voltage signal of output promotes, and in order to compensate the pressure drop on diode, thus avoids the first voltage signal and is cut
Ripple, it is ensured that the normal output of the first voltage signal；Wherein, Level shifter module is equal to two to the lifting values of the first voltage signal
Forward voltage drop value on the pipe of pole.
The step of the most various methods divides, and is intended merely to describe clear, it is achieved time can merge into a step or
Some step is split, is decomposed into multiple step, as long as comprising identical logical relation, all at the protection domain of this patent
In；To adding inessential amendment in algorithm or in flow process or introducing inessential design, but do not change its algorithm
With the core design of flow process all in the protection domain of this patent.
It will be understood by those skilled in the art that the respective embodiments described above are to realize the specific embodiment of the present invention,
And in actual applications, can to it, various changes can be made in the form and details, without departing from the spirit and scope of the present invention.
Claims (8)
1. a video output circuit, it is characterised in that be connected between the outfan of video chip and video output terminal；Its
In, described video output circuit comprises: power supply, Level shifter module and diode；
First port of described Level shifter module is connected with the outfan of described video chip, the of described Level shifter module
Two-port netwerk is connected with the positive pole of described power supply, and the 3rd port of described Level shifter module is connected with the positive pole of described diode,
4th port ground connection of described Level shifter module；The negative pole of described diode is connected with described video output terminal；Described electricity
The minus earth in source；
After the first voltage signal that described video chip is exported by described Level shifter module promotes, exported by described diode
To described video output terminal；Wherein, described Level shifter module is equal to described two to the lifting values of described first voltage signal
Forward voltage drop value on the pipe of pole.
Video output circuit the most according to claim 1, it is characterised in that described Level shifter module comprises the first resistance
R1 and audion Q1；
The base stage of described Q1 is the first port of described Level shifter module；One end of described R1 is described Level shifter module
Second port, the other end is connected with the emitter stage of described Q1, the 3rd end of the most described Level shifter module of transmitting of described Q1
Mouthful；4th port of the most described Level shifter module of current collection of described Q1.
Video output circuit the most according to claim 1, it is characterised in that also comprise filtration module；
Described filtration module one end is connected with the positive pole of described power supply, other end ground connection.
Video output circuit the most according to claim 3, it is characterised in that described filtration module comprises electric capacity C1；
Described C1 one end is connected with the positive pole of described power supply, other end ground connection.
Video output circuit the most according to claim 1, it is characterised in that also comprise current/voltage modular converter；
One end of described current/voltage modular converter is connected with the outfan of described video chip, other end ground connection；
The current signal of current mode video frequency output in described video chip is converted into described by described current/voltage modular converter
One voltage signal.
Video output circuit the most according to claim 5, it is characterised in that described current/voltage modular converter comprises second
Resistance R2；
Described R2 one end is connected with the outfan of described video chip, other end ground connection.
7. a multimedia terminal, it is characterised in that comprise the video output circuit as according to any one of claim 1 to 6.
8. a picture output method, it is characterised in that be applied to the video frequency output electricity according to any one of claim 1 to 6
Road, described picture output method comprises the steps of
The first voltage signal exported by described video chip promotes；
By the first voltage signal after voltage increase through the output of described diode to described video output terminal；
Wherein, the lifting values of described first voltage signal is equal to the forward voltage drop value on described diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610184634.6A CN106060436A (en) | 2016-03-28 | 2016-03-28 | Video output method, video output circuit and multimedia terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610184634.6A CN106060436A (en) | 2016-03-28 | 2016-03-28 | Video output method, video output circuit and multimedia terminal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106060436A true CN106060436A (en) | 2016-10-26 |
Family
ID=57484192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610184634.6A Pending CN106060436A (en) | 2016-03-28 | 2016-03-28 | Video output method, video output circuit and multimedia terminal |
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Citations (7)
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|---|---|---|---|---|
| CN2759031Y (en) * | 2004-11-02 | 2006-02-15 | 海信集团有限公司 | VF protection circuit |
| CN201042052Y (en) * | 2007-02-13 | 2008-03-26 | 青岛海信电器股份有限公司 | A video output circuit and TV set with above video output circuit |
| CN201215989Y (en) * | 2008-06-23 | 2009-04-01 | 青岛海信电器股份有限公司 | Voltage stabilizing circuit and television set having the voltage stabilizing circuit |
| CN101527450A (en) * | 2009-04-10 | 2009-09-09 | 合肥金星机电科技发展有限公司 | Protective device for video transmission |
| CN201503689U (en) * | 2009-08-21 | 2010-06-09 | 鸿富锦精密工业（深圳）有限公司 | Video equipment |
| CN102098420A (en) * | 2011-02-24 | 2011-06-15 | 广州视源电子科技有限公司 | Video signal output circuit |
| CN202374388U (en) * | 2011-12-21 | 2012-08-08 | 天津市亚安科技股份有限公司 | Circuit capable of achieving multi-path output of same video |
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2016
- 2016-03-28 CN CN201610184634.6A patent/CN106060436A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2759031Y (en) * | 2004-11-02 | 2006-02-15 | 海信集团有限公司 | VF protection circuit |
| CN201042052Y (en) * | 2007-02-13 | 2008-03-26 | 青岛海信电器股份有限公司 | A video output circuit and TV set with above video output circuit |
| CN201215989Y (en) * | 2008-06-23 | 2009-04-01 | 青岛海信电器股份有限公司 | Voltage stabilizing circuit and television set having the voltage stabilizing circuit |
| CN101527450A (en) * | 2009-04-10 | 2009-09-09 | 合肥金星机电科技发展有限公司 | Protective device for video transmission |
| CN201503689U (en) * | 2009-08-21 | 2010-06-09 | 鸿富锦精密工业（深圳）有限公司 | Video equipment |
| CN102098420A (en) * | 2011-02-24 | 2011-06-15 | 广州视源电子科技有限公司 | Video signal output circuit |
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Application publication date: 20161026 |
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