CN1059299C - Anti-low-frequency-interference horizontal scan grating circuit - Google Patents
Anti-low-frequency-interference horizontal scan grating circuit Download PDFInfo
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- CN1059299C CN1059299C CN97103014A CN97103014A CN1059299C CN 1059299 C CN1059299 C CN 1059299C CN 97103014 A CN97103014 A CN 97103014A CN 97103014 A CN97103014 A CN 97103014A CN 1059299 C CN1059299 C CN 1059299C
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Abstract
The present invention relates to an anti low-frequency interference horizontal scanning grating circuit which comprises a main resonance capacitor and a plurality of switched type branching resonant capacitors, wherein the branching resonant capacitors are parallel to the main resonance capacitor and are used for compensating horizontal linearity. Both ends of the main resonance capacitor in the horizontal scanning grating circuit are parallel to an oscillation attenuation circuit which comprises an attenuation capacitor and an attenuation resistor which are serially connected, and the attenuation capacitor and the attenuation resistor are in parallel connection at both ends of the main resonance capacitor. Both ends of the attenuation resistor are in parallel connection with a diode, an anode of the diode is connected with a ground terminal, a cathode is connected with a connection point of the attenuation capacitor and the attenuation resistor, and then the attenuation capacitor can not influence the horizontal linearity.
Description
Present invention is directed to a kind of display control circuit, be meant a kind of horizontal sweep grating circuit (horizontal scan raster circuit) especially, can effectively improve or eliminate the noise that horizontal-deflection output circuit produced in general multiple (multisync) display frequently, the low-frequency disturbance (jitters) that when horizontal deflection IC (Integrated Circuit) is delivered in back coupling, is caused.
Low-frequency disturbance in the display, suitable mostly of the reason that causes are a kind of quite insoluble problems.Particularly when display operation during, for example under the 31.5KHz VGA pattern, just can directly see the phenomenon of low-frequency disturbance from the picture of general display in the low frequency sequential.When low-frequency disturbance took place, bad rating phenomenons such as (flicker) may appear flashing in picture, therefore how to reduce low-frequency disturbance and equally also be when making display the problem that must solve.
The reason of general display generation low-frequency disturbance mainly can be divided three classes:
(1) first kind reason of generation low-frequency disturbance is to be caused by the inconsistent institute of the frequency of operation of the horizontal deflecting circuit in exchange type power (switching power supply) and the display.Therefore basically, this interference source is because assembly element causes, and can see through and adjust assembly element, makes the agreeing property of frequency of operation of exchange type power and horizontal deflecting circuit, uses the low-frequency disturbance of eliminating this source.
(2) second class reasons then are that circuit is subjected to the vertical scanning frequency influence, or this line-to-ground mis-arrange causes by the phase-locked loop of horizontal deflection IC itself (phase locked loop is called for short PLL).This interference source then can see through adequate shielding (shielding) processing and be eliminated, and for example the cloth exchange line of PLL peripheral circuit is avoided vertical synchronizing signal and circuit.
The interference source of (3) the 3rd classes then is that the noise that produced by horizontal-deflection output circuit is feedback and caused to horizontal deflection IC.The interference source of this class is the effect that is caused by horizontal-deflection output circuit self back coupling, therefore difficult the removal.The low-frequency disturbance in this source is obvious especially to the image of so-called complex frequency display.
Purpose of the present invention promptly is to eliminate the low-frequency disturbance in the 3rd class source.Before the low-frequency disturbance in this source of explanation, the operation principle of horizontal-deflection output circuit in the general complex frequency type display is described at first.
Fig. 1 represents an example of the detailed circuit diagram of horizontal-deflection output circuit in the known complex frequency type display.Mean level deflection circuit output system is formed, is used at horizontal deflection device L by horizontal deflection IC1, horizontal drive level 3, horizontal output stage 5, automatic frequency control (Automatic Frequency Control is called for short AFC) feedback circuit 7
HThe last deflection current that produces required zigzag waveform.As shown in Figure 1, level control voltage is a direct current voltage, in order to the scanning frequency of the required generation of controlling level deflection circuit output.Horizontal deflection IC1 just can utilize its inner oscillator (not shown) to produce required horizontal scanning pulse signal after receiving this level control voltage.Horizontal drive level 3 is made of power transistor Q1, resistance R 1 and capacitor C 1, when its base stage receives the scanning pulse signal that horizontal deflection IC1 sent here, produce the pulse signal (as shown in the figure) of rectangle with the working method that is similar to switch, see through isolating transformer T1 and be sent to horizontal output stage 5.The ON time of transistor Q1 can determine the pulse duration of its output rectangular pulse, controls the sweep time of each horizontal scanning line.5 of horizontal output stages are made of transistor Q2 and damper diode D1, and its output is connected to horizontal deflection device L
HWith its main resonance capacitor C S, use at horizontal deflection device L
HThe required deflection current of last generation.Damper diode D1 and capacitor C
FEffect be to reduce shock excitation oscillation effect in the deflection current, particularly on sweep time corresponding to the grating left side.The effect of AFC feedback circuit 7 then is that phase control when being horizontal sweep is on the correct display position of picture.AFC feedback circuit 7 takes out signal by the collection utmost point of transistor Q2, feedbacks to horizontal deflection IC1, uses and reaches phase-locked loop (phase-locked loop is called for short PLL), and the picture when using controlling level scanning is stable.
When the horizontal frequency in the complex frequency type display changes, can see through the resonant capacitance value that change is series at horizontal deflection device LH, come the different time sequential routines is controlled its horizontal linearity.General common control mode is to utilize the plural groups switching regulator electric capacity that is parallel to main resonance capacitor C S, produces required resonant capacitance value with the selectivity conduction mode.In addition, when the frequency in time sequential routine is lower, required resonant capacitance value is just bigger.As shown in Figure 1, three groups of switching regulator electric capacity (C
S1With SW1, C
S2With SW2, C
S3And SW3) be parallel to main resonance capacitor C S, when horizontal frequency need change, then the microcontroller by the complex frequency type display produced control signal to switch SW 1, SW2, SW3, the feasible corresponding resonant capacitance C of branch
S1, C
S2, C
S3The state that presents conducting uses producing different equivalent resonant capacitances.Therefore, for the operator scheme of different frequency, horizontal linearity is controlled within the specific specification.
Because the horizontal-deflection output circuit in the display is the circuit of a kind of high voltage, big electric current, therefore, be easy to the noise in the circuit is transferred back to horizontal deflection IC1 through AFC feedback circuit 7 or grounded circuit.Though AFC feedback circuit 7 itself has the function of eliminating noise, under low-frequency operating environment (as 31.5KHz VGA pattern), some noise still can't be eliminated by the AFC feedback circuit, disturbs just therefore can produce the noise of low frequency on picture.
As the resonant capacitance C of branch
S1, C
S2, C
S3When being in the state of conducting, horizontal yoke current just can flow into respectively in branch's resonant capacitance of main resonance capacitor C S and conducting.Yet, because main resonance capacitor C S and the resonant capacitance C of branch
S1, C
S2, C
S3Capacitance and volume quite big, so when wiring become broad, lead-in wire of each interval become longer, this will make that free noise is very easy and enter in the circuit.Usually seeing through this mode, to enter the noise of circuit quite big, therefore utilizes the AFC feedback circuit to eliminate fully, and just can present the interference of low frequency noise on picture.
On the other hand, because main resonance capacitor C S and the resonant capacitance C of branch
S1, C
S2, C
S3Between layout lead-in wire become very long, so lead-in wire is very easy to occur the characteristic of inductance, and with the effect of each resonant capacitance generation resonance, cause another kind of noise interference source.These noises see through grounded circuit or AFC feedback circuit in regenerative mode, pass horizontal deflection IC1 back, the horizontal phase of picture are interfered, the situation that occurs trembling.
According to the above, the low-frequency disturbance that this class is caused by branch's resonant capacitance in the complex frequency type display, therefore be difficult to utilize traditional noise isolation technology to be eliminated, be necessary the low-frequency disturbance that caused at branch's resonant capacitance, propose the processing mode of another kind of anti-low-frequency disturbance.
In view of this, main purpose of the present invention, be to provide a kind of horizontal sweep grating circuit of anti-low-frequency disturbance, particularly at the complex frequency type display, use and reduce or eliminate in the scanning circuit branch's resonant capacitance and its lead-in wire, see through and feedback and produce low-frequency disturbance via the noise that resonance produced.
According to above-mentioned purpose, the invention provides a kind of horizontal sweep grating circuit of anti-low-frequency disturbance, in the complex frequency type display, mainly be to reduce in order to the caused low-frequency disturbance of the resonant capacitance of compensation level linearity.As previously mentioned, have the main resonance electric capacity of connecting in the horizontal sweep grating circuit with horizontal deflection device, and several switching regulator branch resonant capacitances in parallel with above-mentioned main resonance electric capacity.Main resonance electric capacity and above-mentioned switching regulator branch resonant capacitance promptly are to be used for the compensation level linearity.But in the present invention, have more the oscillatory extinction circuit that is parallel to main resonance electric capacity two ends in the horizontal sweep grating circuit, therebetween in order to suppress above-mentioned switching regulator branch's resonant capacitance and to go between because the oscillator signal that resonance produced.This oscillatory extinction circuit comprises the decay usefulness capacitor that is connected in series and decays and use resistor, is parallel to the two ends of above-mentioned main resonance electric capacity.At the two ends then in parallel diode of decay with resistor, its anode is connected to earth terminal, and its negative electrode is connected to decay and uses capacitor and decay with on the tie point of resistor, uses preventing that decay from having influence on horizontal linearity with capacitor.In practical application, decay uses the capacitance of capacitor approximately less than about 1 μ F, can avoid having influence on horizontal linearity; Decay then is approximately T with the resistance value of resistor
ON/ 3C
D, T wherein
ONThe transistorized ON time of horizontal output stage of expression horizontal sweep grating circuit, C
DThe expression decay capacitance of capacitor.
For above-mentioned purpose of the present invention, feature and advantage can be become apparent, special in conjunction with a most preferred embodiment, and conjunction with figs., be described in detail below:
Brief Description Of Drawings:
Fig. 1 represents the detailed circuit diagram of the horizontal-deflection output circuit of known complex frequency type display;
Fig. 2 represents the block diagram of horizontal-deflection output circuit of the anti-low-frequency disturbance of the embodiment of the invention;
Fig. 3 represents the detailed circuit diagram of horizontal-deflection output circuit of the anti-low-frequency disturbance of the embodiment of the invention.
Embodiment:
The horizontal sweep grating circuit of anti-low-frequency disturbance of the present invention, mainly be at the main resonance electric capacity of using as linear compensation in the complex frequency type display and branch's resonant capacitance, be coupled to noise when going between long, or lead-in wire becomes inductive and when producing noise with resonant capacitance resonance, can effectively suppress, use and avoid this noise source to feedback to horizontal control IC through AFC feedback circuit or earth terminal.Particularly for the noise that lead-in wire and each resonant capacitance resonance produce, traditional AFC feedback circuit is to reach the purpose of eliminating noise fully, and the noise source of this class produced by circuit itself, utilizes general shield technology also can't solve.Therefore, in the present invention, the oscillator signal that adopts an oscillatory extinction circuit (dampingcircuit) directly to suppress resonance to be produced sees through this mode, just can effectively suppress the generation of resonance noise.
Fig. 2 represents the block diagram of horizontal-deflection output circuit of the anti-low-frequency disturbance of present embodiment.Oscillatory extinction circuit 9 is to be connected in the main resonance capacitor C in parallel on circuit relationships
STwo ends, as shown in Figure 2.The on off state of switch SW 1, SW2, SW3 can be controlled the corresponding resonant capacitance C of branch
S1, C
S2, C
S3Conducting state.When arbitrary switch was opening, horizontal deflection device L flowed through
HDeflection current will be according to the main resonance capacitor C
SCarry out electric current with the capacitance of branch's resonant capacitance of conducting and distribute, and flow on therebetween the lead-in wire.As previously mentioned, the inessential resonance signal that inductanceization caused because lead-in wire is long just can see through and be connected in earth terminal and horizontal deflection device L
HWith the main resonance capacitor C
SBetween the oscillatory extinction circuit 9 of tie point, in addition suitable attenuation processing.Therefore, when practical wiring was used, oscillatory extinction circuit 9 can be configured near the main resonance capacitor C as far as possible
SSide can prevent that the oscillator signal noise from seeing through AFC feedback circuit 7 and feedbacking to horizontal deflection IC1, uses and obtains better barriering effect.
Fig. 3 then represents the detailed circuit diagram of horizontal-deflection output circuit of the anti-low-frequency disturbance of present embodiment.In Fig. 3, oscillatory extinction circuit 9 is by decay electricity consumption container C
D, the decay constitute with resistor R2 and diode D2.Decay electricity consumption container C
DAn end be connected to the main resonance capacitor C
SWith horizontal deflection device L
HTie point, the other end then is connected to decay and uses resistor R2.That is, decay electricity consumption container C
DWith resistor R 2 is to be connected to each other in the mode of connecting, and is connected to the main resonance capacitor C in parallel
SOn.When deflection current flow through branch's resonant capacitance of conducting and lead-in wire therebetween, and when causing the vibration noise, decay electricity consumption container C
DCan utilize the principle of oscillatory extinction with resistor R2 with decaying, suppress the generation of this noise, use the purpose that reaches anti-low-frequency disturbance.
In the present embodiment, decay electricity consumption container C
DBe to be connected in the main resonance capacitor C with parallel way
SOn each branch's resonant capacitance, therefore may have influence on the function of its compensation level linearity.So can utilize the dual mode electricity consumption container C that prevents to decay in the present embodiment
DHave influence on horizontal linearity.
First kind of mode is at decay diode D in the resistor R2 two ends parallel connection
2, its plus earth, its negative electrode then is connected to decay electricity consumption container C
DWith the tie point of decay with resistor R2.Diode D2 is used for reverse conducting decay electricity consumption container C
D, use and avoid its effects to normal horizontal linearity.Therefore, diode D2 preferably has the characteristic that can be used in big electric current, for example the diode of an ampere (1A).
The second way then is to use the decay capacitor C with smaller capacitive value
D, in the hope of not influencing the operation of horizontal linearity compensation.At this moment, decay electricity consumption container C
DCan select the electric capacity that is lower than 1 μ F for use.When decay electricity consumption container C
DCapacitance decision after, resistance value with resistor R2 according to this just can determine to decay.
In the present embodiment, decay uses the resistance value of resistor R2 greatly about T
ON/ 3C
DAbout, wherein, T
ONThe ON time of horizontal output stage transistor Q2 of representing the grating circuit of above-mentioned horizontal sweep, C
DRepresent above-mentioned decay electricity consumption container C
DCapacitance.The size of general this resistance value is greatly about about number K Ω.Yet above-mentioned preferable capacitance and resistance value are not in order to limit the present invention, when practical application, and the wire length when above-mentioned numerical value can be according to the capacitance of each branch's resonant capacitance and its practical wiring and adjusting.
Utilize above-mentioned horizontal sweep output circuit, when directly applying to the complex frequency type display, can effectively solve the problem of display low-frequency disturbance really with oscillatory extinction circuit.Via reality test gained, the display of above-mentioned horizontal sweep output circuit is housed, before display screen about 30cm with naked-eye observation, almost cannot see any low-frequency disturbance and picture jitter, the picture quality of display significantly improves really.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to limit the present invention; any those who familiarize themselves with the technology; in not breaking away from design of the present invention and scope; when can doing a little change or retouching, so protection scope of the present invention is as the criterion as the scope person of defining that look claim of the present invention.
Claims (6)
1, a kind of horizontal sweep grating circuit of anti-low-frequency disturbance, in the complex frequency type display, in order to reduce the caused low-frequency disturbance of resonant capacitance in the complex frequency type display, has the main resonance electric capacity of connecting in the described horizontal sweep grating circuit with horizontal deflection device, and a plurality of and above-mentioned main resonance electric capacity branch's resonant capacitance in parallel, described main resonance electric capacity and described branch resonant capacitance is characterized in that in order to the compensation level linearity:
Have an oscillatory extinction circuit, be parallel to the two ends of described main resonance electric capacity, in order to suppress described branch resonant capacitance by the oscillator signal that resonance produced, this oscillatory extinction circuit comprises:
Capacitor is used in one decay, and the one end is connected to the tie point of described main resonance electric capacity and described horizontal deflection device;
One decay uses resistor, its two ends to be connected to described decay respectively with between the other end and earth terminal of capacitor; And
One diode, its anode is connected to earth terminal, and its negative electrode is connected to resistor is used in described decay with capacitor and described decay tie point.
2, horizontal sweep grating circuit as claimed in claim 1 is characterized in that, described decay uses the capacitance of capacitor approximately less than 1 μ F.
3, horizontal sweep grating circuit as claimed in claim 1 is characterized in that, described decay is about T with the resistance value of resistor
ON/ 3C
D, T
ONThe transistorized ON time of horizontal output stage of representing described horizontal sweep grating circuit, C
DRepresent the capacitance of described decay with capacitor.
4, a kind of complex frequency type display, it has the horizontal sweep grating circuit, use and on horizontal deflection device, produce horizontal yoke current, it has a main resonance electric capacity of connecting with described horizontal deflection device, and a plurality of and described main resonance electric capacity branch's resonant capacitance in parallel, horizontal linearity during in order to compensation different scanning frequencies operations is characterized in that
Have an oscillatory extinction circuit in the described horizontal sweep grating circuit, be parallel to the two ends of described main resonance electric capacity, in order to suppress described branch resonant capacitance by the oscillator signal that resonance produced, this oscillatory extinction circuit comprises:
Capacitor is used in one decay, and the one end is connected to the tie point of described main resonance electric capacity and described horizontal deflection device;
One decay uses resistor, its two ends to be connected to described decay respectively with between the other end and earth terminal of capacitor; And
One diode, its anode is connected to earth terminal, and its negative electrode is connected to resistor is used in described decay with capacitor and described decay tie point.
5, complex frequency type display as claimed in claim 4 is characterized in that, described decay uses the capacitance of capacitor approximately less than 1 μ F.
6, complex frequency type display as claimed in claim 4 is characterized in that, described decay is about T with the resistance value of resistor
ON/ 3C
D, T
ONThe transistorized ON time of horizontal output stage of representing described horizontal sweep grating circuit, C
DRepresent the capacitance of described decay with capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97103014A CN1059299C (en) | 1997-03-10 | 1997-03-10 | Anti-low-frequency-interference horizontal scan grating circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97103014A CN1059299C (en) | 1997-03-10 | 1997-03-10 | Anti-low-frequency-interference horizontal scan grating circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1193238A CN1193238A (en) | 1998-09-16 |
| CN1059299C true CN1059299C (en) | 2000-12-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN97103014A Expired - Fee Related CN1059299C (en) | 1997-03-10 | 1997-03-10 | Anti-low-frequency-interference horizontal scan grating circuit |
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| Country | Link |
|---|---|
| CN (1) | CN1059299C (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1040895A (en) * | 1988-08-26 | 1990-03-28 | 三星国际有限公司 | The automatic horizontal holder circuit of multi-system receiver |
-
1997
- 1997-03-10 CN CN97103014A patent/CN1059299C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1040895A (en) * | 1988-08-26 | 1990-03-28 | 三星国际有限公司 | The automatic horizontal holder circuit of multi-system receiver |
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| Publication number | Publication date |
|---|---|
| CN1193238A (en) | 1998-09-16 |
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Owner name: BENQ ELECTRONS STOCK CO., LTD. Free format text: FORMER NAME OR ADDRESS: MINGHONG STOCK CO., LTD. |
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Patentee after: Benq Corp. Patentee before: Mingqi Computer Co., Ltd. |
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Owner name: BENQ MOTOR CO., LTD. Free format text: FORMER NAME OR ADDRESS: BENQ ELECTRONS STOCK CO., LTD. |
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Granted publication date: 20001206 |