CN101018288B - Circuit for outputting image signal - Google Patents

Circuit for outputting image signal Download PDF

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Publication number
CN101018288B
CN101018288B CN2006101567005A CN200610156700A CN101018288B CN 101018288 B CN101018288 B CN 101018288B CN 2006101567005 A CN2006101567005 A CN 2006101567005A CN 200610156700 A CN200610156700 A CN 200610156700A CN 101018288 B CN101018288 B CN 101018288B
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China
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circuit
output
signal
resistance
picture signal
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CN2006101567005A
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CN101018288A (en
Inventor
小川利行
土桥永祥
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Mitsumi Electric Co Ltd
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Mitsumi Electric Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/18—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
    • H03F1/0216—Continuous control
    • H03F1/0233—Continuous control by using a signal derived from the output signal, e.g. bootstrapping the voltage supply

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Picture Signal Circuits (AREA)
  • Controls And Circuits For Display Device (AREA)

Abstract

The invention relates to an video signal output circuit outputting the video signal from the output terminal. The invention aims to provide a video signal output circuit which doesn't need to couple elements for removing direct current component such as capacitance. The circuit comprises: an amplified circuit for amplifying the video signal; an output circuit for outputting earth electrical level when the amplified circuit has no signal.

Description

Circuit for outputting image signal
Technical field
The present invention relates to a kind of circuit for outputting image signal, particularly from the circuit for outputting image signal of lead-out terminal output image signal.
Background technology
In recent years, the mobile phone of digital camera, subsidiary camera etc. obtains the portable vision facilities of picture signal and is popularized, and is provided with output end of image of output image signal in these equipment.At this moment, the regulation according to the JEITA standard has following regulation: the flip-flop of exporting when no signal is 0 ± 0.1V.For this reason, between the image output circuit of vision facilities output image signal and lead-out terminal, be connected in series with coupling (coupling) electric capacity.
Fig. 4 represents the frame assumption diagram of an existing example.
Vision facilities 11 has the sub-Tvout of output end of image, will pass through image driver IC22 and coupling capacitor C0 by the picture signal that treatment circuit 21 provides, and outputs to other vision facilities 12 from lead-out terminal Tvout.
Image driver IC22 for example is made of a slice semiconductor integrated circuit, and its structure is amplifier 31,32, clamp circuit 33, operational amplifier (op amp) 34, resistance R 11～R15.The supply voltage that image driver IC22 utilizes battery 23 to supply with drives, and from the picture signal of output electronics Ticout output by treatment circuit 21 supplies.
In addition, image driver IC22 has energy-conservation (power save) terminal Tps.Supply with energy-conservation signal from treatment circuit 21 to energy-conservation terminal Tps.Image driver IC22 is when providing energy-conservation signal by treatment circuit 21, and making signal is no signal condition.
Image driver IC22 provides picture signal from treatment circuit 21 to input terminal Ticin.Offer the picture signal of input terminal Ticin, supply to the non-inverting input of operational amplifier 34.Operational amplifier 34 is constituted as: setover by resistance R 11～R14, amplifier 31,32 and 33 pairs of non-inverting inputs of clamp circuit and reversed-phase output, feed back by resistance R 15; Resistance R 11～R15, amplifier 31,32 and clamp circuit 33 constitute noninverting amplifying circuit together.
Resistance R 11～R13 is for being connected in series, one end is connected on the power supply terminal Tvcc, other end ground connection, power source voltage Vcc is carried out dividing potential drop, on the tie point of resistance R 11 and resistance R 12, produce voltage V11, on the tie point of resistance R 13 and resistance R 12, produce voltage V12.
The voltage V11 that produces on the tie point of resistance R 11 and resistance R 12 offers the non-inverting input of operational amplifier 34 with 1.2V by amplifier 31.The voltage V12 that produces on the tie point of resistance R 12 and resistance R 13 is 2.1V.Voltage V12 is provided to an end of resistance R 14 by amplifier 32.The output voltage V a of amplifier 32 is 2.1V.Make the output voltage V a step-down of amplifier 32 and be applied on the inverting input of operational amplifier 34 by resistance R 14.
Carry out step-down by resistance R 14, and supply to the inverting input of operational amplifier 34.The bias voltage Vc of the inverting input of operational amplifier 34 is 1.2V.
Clamp circuit 33 is connected with the non-inverting input of operational amplifier 34, fixedly the voltage of the non-inverting input of operational amplifier 34.The output of operational amplifier 34 is provided to vision facilities 12.
Fig. 5 represents the frame assumption diagram of operational amplifier 34.
Operational amplifier 34 is made of amplifying circuit 41 and output circuit 42.41 pairs of picture signals of amplifying circuit are amplified and are offered output circuit 42.
Amplifying circuit 41 amplifies input terminal Ticin signal supplied, and offers output circuit 42.
Output circuit 42 is made up of transistor Q11 and transistor Q12.
Transistor Q11 is made of the PNP transistor, and emitter is connected with power supply terminal Tvcc, and collector electrode is connected with lead-out terminal Ticout, and the output of amplifying circuit 41 is provided to base stage.Transistor Q12 is made of NPN transistor, and collector electrode is connected with lead-out terminal Ticout, and grounded emitter provides the output of amplifying circuit 41 to base stage.
Output circuit 42 is according to coming driving transistors Q11, Q12 from the picture signal of amplifying circuit 41, from the signal of lead-out terminal Ticout output corresponding to picture signal.
Fig. 6 represents the movement oscillogram of an existing example.The picture signal that Fig. 6 (A) expression provides to input terminal Ticin, Fig. 6 (B) expression is from the picture signal of the lead-out terminal Ticout output of image driver IC22, and Fig. 6 (C) expression is from the picture signal of external image lead-out terminal Tvout output.
Input terminal Ticin is by on the clamp circuit 33 stuck-at-.2V, so lead-out terminal Ticout, the sync-tip level of picture signal shown in Fig. 6 (A) (sync tip level) is 1.2V, at the tie point output image signal that does not have letter resistance (R31).
Operational amplifier 34 constitutes noninverting amplifying circuit with resistance R 14, R15, picture signal is carried out noninverting amplification and exports from lead-out terminal Ticout.At this moment, as shown in Figure 6, therefore by output circuit 42 ground connection of transistor Q12, even when no signal, also produce flip-flop about transistor Q12 collector electrode-about 0.3V of emission voltage across poles with operational amplifier 34.Under current state, according to the regulation of JEITA standard, the flip-flop during no signal is not suitable for 0 ± 0.1V.In this case, generally will offer load (with reference to patent documentation 1) by the signal that coupling capacitance has been removed flip-flop.
Therefore, between image driver IC22 and external image lead-out terminal Tvout, be provided with coupling capacitance C0.C0 removes flip-flop by coupling capacitance, can make external image lead-out terminal Tvcout be output as 0V when no signal.
In addition, picture signal is by coupling capacitance C0, so shown in Fig. 6 (C), the potential waveform identical with the area S12 of picture signal side of the positive electrode with the area S11 of picture signal negative side comes output signal.
[patent documentation 1] spy opens flat 11-298991 communique
But existing image output circuit is in order to meet the regulation of JEITA standard, need connect between the output of image driver IC22 and lead-out terminal Tvout and insert the coupling capacitance that is used to remove flip-flop, therefore is difficult to realize the miniaturization of vision facilities.
In view of above some, the object of the invention provides a kind of image output circuit, this circuit does not need coupling capacitance etc. to be used to remove the element of flip-flop on lead-out terminal.
Summary of the invention
The circuit for outputting image signal of output image signal of the present invention (131), this circuit is characterised in that to have: the amplifying circuit (41) that picture signal is amplified; Make when being output as no signal at amplifying circuit (41) and to be output as earth level.
The invention is characterized in that output circuit (131) is exported the reference potential of picture signal as earth level.Feature of the present invention is that also the reference potential of picture signal is sync-tip level (sync tip level).
In addition, feature of the present invention is that also output circuit (131) has: the transistor (Q11) corresponding to the electric current of picture signal is provided; And Xiang Yiduan goes up that to be supplied with electric current corresponding to picture signal, made the other end by described transistor (Q11) be the resistance (R31) of earth level, from the tie point output image signal of transistor (Q11) with resistance (R31).
The invention is characterized in that output circuit (131) is connected to from outside lead-out terminal (Tvout) output signal output.
In addition, described reference marks only is reference, does not therefore limit the scope of claim.
According to the present invention, by being provided with the amplifier circuit that in the circuit for outputting image signal of output image signal, picture signal is amplified and when the output of amplifier circuit is no signal, making the output circuit that is output as earth level, flip-flop in the time of can making no signal is 0V substantially, so need coupling capacitance be set at lead-out terminal, therefore can reduce peripheral component, and can reduce its erection space, reduce cost.
Description of drawings
Fig. 1 is the frame assumption diagram of one embodiment of the invention.
Fig. 2 is the circuit structure diagram of operational amplifier 124.
Fig. 3 is the movement oscillogram of one embodiment of the invention.
Fig. 4 is the frame assumption diagram of an existing example.
Fig. 5 is the frame assumption diagram of operational amplifier 34.
Fig. 6 is the movement oscillogram of an existing example.
Embodiment
Fig. 1 represents the frame assumption diagram of one embodiment of the invention.Among this figure, to identical component part mark same-sign with Fig. 4, it illustrates omission.
In the vision facilities 100 of present embodiment, the structure of image driver IC111 is different from Fig. 4.The image driver IC111 of present embodiment is made of 1 chip semiconductor integrated circuit, and the structure of operational amplifier 121 is different from operational amplifier shown in Figure 4 34.
Fig. 2 represents the frame assumption diagram of operational amplifier 121.Among this figure, the structure division mark same-sign identical with Fig. 5, it illustrates omission.
In the operational amplifier 121 of present embodiment, the structure of output circuit 131 is different from output circuit shown in Figure 5 42.The output circuit 131 of present embodiment will be exported as earth level from the reference potential of the picture signal of amplifier circuit 41.At this moment, the reference potential of picture signal is a sync-tip level.
The structure of output circuit 131 is: replace the transistor Q12 of output circuit 42 shown in Figure 5, be connected with resistance R 31 between the tie point of the collector electrode of transistor Q11 and lead-out terminal Ticout and ground connection.
Resistance R 31 for example is about 500 Ω.Voltage in the time of can making no signal by replacing transistor Q12 to connect resistance R 31 is 0V substantially, more particularly, it is become about 0.05V.Therefore, exporting even wait the output that makes image driver IC111 to keep intact without coupling capacitance C0, is 0 ± 0.1V in the time of also can satisfying the no signal as the JEITA standard code.
Outside terminal Ticout as the image driver IC111 of output circuit 131 output directly is connected with the outside lead-out terminal Tvout of vision facilities 100, directly exports the output signal of output circuit 131 from the outside lead-out terminal Tvout of vision facilities 100.
Fig. 3 represents the movement oscillogram of one embodiment of the invention.The picture signal that Fig. 3 (A) expression is supplied with to input terminal Ticin, Fig. 3 (B) expression is from the picture signal of lead-out terminal Ticout output.
By clamp circuit 33 with input terminal Ticin stuck-at-.2V, so among the input terminal Ticin shown in Fig. 3 (A), the sync-tip level of picture signal is 1.2V, flip-flop is 1.2V when no signal.
As shown in Figure 2, in the output circuit 131 of operational amplifier 34, therefore with lead-out terminal Ticout ground connection, transistor Q11 is roughly disconnection (off) state when the sync-tip level of picture signal and no signal, is roughly earth level, is roughly 0V through resistance R 31.Thus, coupling capacitance C0 need not be set, the flip-flop in the time of just making the no signal of JEITA standard code is suitable for 0 ± 0.1V.
Therefore, need between the lead-out terminal Ticout of image driver IC111 and outside terminal Tvout, coupling capacitance C0 be set.Thus, can reduce peripheral component and erection space that can downscaled images equipment.In addition, can also reduce cost.
And, according to present embodiment, can obstructed overcoupling electric capacity output image signal, therefore can suppress the decay of the low-frequency component of the picture signal that causes by coupling capacitance C0, thus, can reduce from the distortion of the picture signal of lead-out terminal Tvout output.
In addition, image driver IC111 is disconnection when energy-conservation.At this moment, by resistance R 31 being made as about big resistance, for example 2M Ω, can when energy-conservation, will be suppressed at about 2 μ A from leakage (leak) electric current of outside terminal Tvout.In addition, can also import other signal, supply to other circuit of vision facilities 100 inside from lead-out terminal Tvout.Thus, can when energy-conservation, lead-out terminal Tvout be also used as input terminal.

Claims (5)

1. the circuit for outputting image signal of an output image signal is characterized in that, has:
Amplifying circuit amplifies described picture signal; With
Output circuit makes when described amplifying circuit is output as no signal and is output as earth level.
2. circuit for outputting image signal according to claim 1 is characterized in that,
Described output circuit is exported the reference potential of described picture signal as earth level.
3. circuit for outputting image signal according to claim 2 is characterized in that,
The reference potential of described picture signal is a sync-tip level.
4. circuit for outputting image signal according to claim 1 is characterized in that,
Described output circuit has: supply with the transistor corresponding to the electric current of described picture signal; And resistance, being supplied with electric current corresponding to described picture signal, make the other end of this resistance to an end of this resistance by described transistor is earth level,
Export described picture signal from the tie point of described transistor and described resistance.
5. circuit for outputting image signal according to claim 1 is characterized in that,
Described output circuit is connected into from outside lead-out terminal output signal output.
CN2006101567005A 2006-02-07 2006-12-30 Circuit for outputting image signal Active CN101018288B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2006029777A JP4747862B2 (en) 2006-02-07 2006-02-07 Video signal output circuit
JP2006-029777 2006-02-07
JP2006029777 2006-02-07

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CN101018288A CN101018288A (en) 2007-08-15
CN101018288B true CN101018288B (en) 2010-09-08

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KR (1) KR100983611B1 (en)
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TW (1) TW200746802A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5088099B2 (en) * 2007-11-07 2012-12-05 ミツミ電機株式会社 Video signal amplifier circuit and semiconductor integrated circuit for amplification
JP5578048B2 (en) * 2010-11-29 2014-08-27 ミツミ電機株式会社 Video signal output circuit

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6266089B1 (en) * 1996-12-12 2001-07-24 Rohm Co., Ltd. Image sensing integrated circuit device
US6600513B1 (en) * 1998-01-30 2003-07-29 Sharp Kabushiki Kaisha Charge transfer device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63157571A (en) 1986-12-22 1988-06-30 Sony Corp Synchronizing signal sampling circuit
JPH01233968A (en) * 1988-03-15 1989-09-19 Nec Corp Picture signal dc recovery circuit
JPH09148848A (en) * 1995-11-27 1997-06-06 Hitachi Ltd Broadband signal transmission circuit and amplifier
JPH11112345A (en) * 1997-09-30 1999-04-23 Nec Corp Agc circuit for video
JPH11136039A (en) 1997-10-31 1999-05-21 Sanyo Electric Co Ltd Power amplifying device
JP2004248200A (en) * 2003-02-17 2004-09-02 Sanyo Electric Co Ltd Video recording apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6266089B1 (en) * 1996-12-12 2001-07-24 Rohm Co., Ltd. Image sensing integrated circuit device
US6600513B1 (en) * 1998-01-30 2003-07-29 Sharp Kabushiki Kaisha Charge transfer device

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JP2007214658A (en) 2007-08-23
CN101018288A (en) 2007-08-15
KR100983611B1 (en) 2010-09-24
JP4747862B2 (en) 2011-08-17
KR20070080554A (en) 2007-08-10
TW200746802A (en) 2007-12-16

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