CN1967652A - Synchronizing frequency doubling signal generating device and method - Google Patents
Synchronizing frequency doubling signal generating device and method Download PDFInfo
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- CN1967652A CN1967652A CN 200510123657 CN200510123657A CN1967652A CN 1967652 A CN1967652 A CN 1967652A CN 200510123657 CN200510123657 CN 200510123657 CN 200510123657 A CN200510123657 A CN 200510123657A CN 1967652 A CN1967652 A CN 1967652A
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Abstract
A synchronized multiple frequency signal device includes: an integral switch module, controlled by scanning synchronization signal; a first integral unit, connecting with the integral switch module, integral computation on the scanning synchronization signal of high marks to export the first integral signal; a second integral unit, connecting with the integral switch module, integral computation on the scanning synchronization signal of low marks to export the second integral signal; an addition unit, connecting with the first and second integral units, summing the first and second integral signals to export a multiple frequency modulated signal; and a comparison unit, connecting with the addition unit, comparing the multiple frequency modulated signal and a reference signal, to export the synchronized multiple frequency signal. The invention receives the scanning synchronization signals in LCD display systems, to generate the synchronized multiple frequency signal for the systems, in order to eliminate differential frequency interference generated by the pulse width modulation.
Description
Technical field
A kind of synchronizing frequency doubling signal generating device of the present invention and method, especially refer to a kind of being used in the liquid crystal display systems, the scan-synchronized signal produces synchronizing frequency doubling signal and uses to system in the employing system, with difference frequency interference signals generation device and the method that pulse-width modulation was produced in the elimination system.
Background technology
The user can control transverter (invereter) action by hardware or software, changes with the backlight of the LCDs (LCD PANEL) of lighting or adjust LCD (LCD MONITOR), notebook computer or the brightness in sidelight source.Display is mainly and utilizes pulse-width modulation (Pulsewidth modulation on the market; PWM) mode is lit a lamp and light modulation, and its principle makes its width according to pulse wave produce discontinuous current, and then reaches the purpose of lighting a lamp with light modulation for control the power level (inverter power stage) of transverter according to the width of control pulse wave.
Please refer to Fig. 1, be the circuit block diagram of known not synchronous Wave-wide regulation controlled electric light adjusting type transverter.When the user adjusted the brightness of liquid crystal display systems (being foregoing liquid crystal display or LCDs) picture by the control of software, the microprocessor of liquid crystal display systems (not indicating) can activate PWM unit 10 earlier and light backlight lamp tube 14 with control converter power unit 12.When the brightness of backlight lamp tube 14 is adjusted, microprocessor can be exported a brightness control signal and give PWM unit 10, produce a Wave-wide regulation controlled electric output signal PWMout through the modulation of this PWM unit 10 after relatively and give converter power unit 12, this converter power unit 12 is that the width along with Wave-wide regulation controlled electric output signal PWMout produces vibration, and output current is to light the backlight lamp tube 14 in the liquid crystal display systems, or nonoscillatory then can output current, so promptly can reach the purpose of light modulation.
Yet, adopt the pulse-width modulation mode to light a lamp and light modulation, be full load current when modulation backlight lamp tube 14 " bright ", modulation backlight lamp tube 14 is almost zero load when " secretly ", can cause very big low frequency (being generally 150-250Hz) power supply ripple in this way, when ground connection being difficult for of liquid crystal display systems cut apart, just very easily cause scan-synchronized signal (being generally 60Hz) the difference frequency interference between the two of operating frequency (150-250Hz) with the liquid crystal display systems of Wave-wide regulation controlled electric.
Be to adopt not method of synchronization light modulation among Fig. 1, therefore can't avoid the phenomenon of difference frequency interference, if adopt phase-locked loop (Phase Lock Loop; PLL) then can reach with method of synchronization light modulation or light a lamp.With reference to figure 2, circuit block diagram for the synchronous waves width modulation formula light modulation of known employing phase-locked loop, the scan-synchronized signal of liquid crystal display systems is inputed to the synchronization output signal SYNCout of phase-locked loop unit 11 frequency multiplication output (being generally 180Hz-240Hz) one and scan-synchronized signal Synchronization after phase-locked loop unit 11 is phase-locked, and this a synchronization output signal SYNCout and a brightness control signal input to PWM unit 10 in the lump, modulation through PWM unit 10, relatively, produce a Wave-wide regulation controlled electric output signal PWMout and give converter power unit 12, this converter power unit 12 is along with the width of Wave-wide regulation controlled electric output signal PWMout produces discontinuous current, and then reaches the light modulation purpose.
Owing to consider human eye flicker and noise problem, so the Wave-wide regulation controlled electric dimming mode generally is that the use phase-locked loop has disadvantage under this low frequency in low frequency (150Hz-250Hz) operation down:
When a. low frequency was phase-locked, the synchronization output signal of phase-locked loop unit 11 can produce bigger shake (jitter) so that the electric current instability of the backlight lamp tube 14 of flowing through, and causes backlight lamp tube 14 scintillations.
B. the circuit complexity of phase-locked loop unit 11 and cost height.
Summary of the invention
In view of this, the invention provides a kind of synchronizing frequency doubling signal generating device, be used in the liquid crystal display systems, scan-synchronized signal in the employing system produces synchronizing frequency doubling signal and uses to system, disturb in order to the difference frequency that pulse-width modulation produced in the elimination system, it has circuit advantage simple and with low cost.
A kind of synchronizing frequency doubling signal generating device of the present invention includes: an integration switch unit, be used for receiving the scan-synchronized signal in the liquid crystal display systems, and be the high/low accurate position that is controlled by this scan-synchronized signal, and carry out change action; One first integral unit is connected in this integration switch unit, carries out integral operation when this scan-synchronized signal of high levle, to export a first integral signal; One second integral unit is connected in this integration switch unit, carries out integral operation when this scan-synchronized signal of low level, to export a second integral signal; One adder unit is connected in this first integral unit and this second integral unit, is to add up this first integral signal and this second integral signal, in order to export a frequency multiplication modulating signal; And a comparing unit is connected in this adder unit, is relatively this a frequency multiplication modulating signal and a reference signal, in order to export this synchronizing frequency doubling signal.This synchronizing frequency doubling signal provides in the liquid crystal display systems PWM unit to use, and then reaches and light a lamp synchronously or light modulation, disturbs with the difference frequency that pulse-width modulation was produced in the elimination system.
Above general introduction and ensuing detailed description are all exemplary in nature, in order to further specify claim of the present invention.And about other purpose of the present invention and advantage, will be set forth in follow-up explanation and icon.
Description of drawings
Fig. 1 is the circuit block diagram of known not synchronous Wave-wide regulation controlled electric light adjusting type transverter;
Fig. 2 is the circuit block diagram of the synchronous waves width modulation formula light modulation of known employing phase-locked loop;
Fig. 3 is that the synchronizing frequency doubling signal generating device of preferable first embodiment of the present invention is used in the light adjusting circuit block schematic diagram in the liquid crystal display systems;
Fig. 4 is that the synchronizing frequency doubling signal generating device of preferable second embodiment of the present invention is used in the lamp circuit block schematic diagram in the liquid crystal display systems;
Fig. 5 is the synchronizing frequency doubling signal generating device circuit box synoptic diagram of preferred embodiment of the present invention;
Fig. 6 is the synchronizing frequency doubling signal generating device circuit diagram of preferred embodiment of the present invention; And
Fig. 7 is the circuit waveform synoptic diagram of Fig. 6.
Symbol description:
PWM unit 10
Phase-locked loop unit 11
Converter power unit 12
Liquid crystal display systems 2
Synchronizing frequency doubling signal generating device 20
First integral unit 202
Second integral unit 204
Adder unit 206
Phase inverter 207
Comparing unit 208
Scan-synchronized signal S1
Synchronizing frequency doubling signal S2
First integral signal S3
Second integral signal S4
Frequency multiplication modulating signal S5
Anti-phase synchronizing frequency doubling signal S6
Reference signal VREF
PWM unit 22
Converter power unit 24
Wave-wide regulation controlled electric output signal PWMout
Embodiment
Please refer to Fig. 3, for the synchronizing frequency doubling signal generating device of preferable first embodiment of the present invention is used in light adjusting circuit block schematic diagram in the liquid crystal display systems.Liquid crystal display systems 2 includes a synchronous frequency doubling signal generating device 20, a PWM unit 22, a converter power unit 24 and a backlight lamp tube 26 at least.One scan synchronizing signal S1 in synchronizing frequency doubling signal generating device 20 receiving systems, and then generation is synchronized with the synchronous frequency-doubled signal S2 output of scan-synchronized signal S1, a this synchronizing frequency doubling signal S2 and a brightness control signal input to PWM unit 22 in the lump, after the modulation of PWM unit 22, comparison, produce a Wave-wide regulation controlled electric output signal PWMout and give converter power unit 24, this converter power unit 24 is along with the width of Wave-wide regulation controlled electric output signal PWMout produces discontinuous current, and then reaches the light modulation purpose to backlight lamp tube 26.In the application of first embodiment, scan-synchronized signal S1 is the vertical synchronizing signal in the system.
Please refer to Fig. 4, for the synchronizing frequency doubling signal generating device of preferable second embodiment of the present invention is used in lamp circuit block schematic diagram in the liquid crystal display systems.Second embodiment and aforesaid first embodiment compare down, the synchronizing frequency doubling signal generating device 20 of second embodiment is used as the inverter frequency of operation and supplies the cold cathode fluorescent lamp use of lighting a lamp, and synchronous with its scan-synchronized signal S1 that is received, scan-synchronized signal S1 is the horizontal-drive signal in the system.Simultaneously, the second embodiment effect is to light a lamp, so need not to receive brightness control signal.
Please refer to Fig. 5, be the synchronizing frequency doubling signal generating device circuit box synoptic diagram of preferred embodiment of the present invention.Synchronizing frequency doubling signal generating device 20 includes: an integration switch unit 201 receives one scan synchronizing signal S1, is the high/low accurate position that is controlled by this scan-synchronized signal S1, and carries out change action; One first integral unit 202 is connected in this integration switch unit 201, carries out integral operation when this scan-synchronized signal S1 of high levle, to export a first integral signal S3; One second integral unit 204 is connected in this integration switch unit 201, carries out integral operation when this scan-synchronized signal S1 of low level, to export a second integral signal S4; One adder unit 206 is connected in this first integral unit 202 and this second integral unit 204, is to add up this first integral signal S3 and this second integral signal S4, in order to export a frequency multiplication modulating signal S5; And a comparing unit 208 is connected in this adder unit 206, is relatively this a frequency multiplication modulating signal S5 and a reference signal Vref, in order to export this synchronizing frequency doubling signal S2.
With reference to figure 5, synchronizing frequency doubling signal generating device 20 further includes a phase inverter 207 and is connected in this comparing unit 208 again, and this phase inverter 207 receives this frequency multiplication modulating signal S5 to produce reverse sync frequency-doubled signal S6 output.Further include a protected location 209 and be connected in this integration switch unit 201 and this phase inverter 207; when this scan-synchronized signal S1 stops; in order to stop this synchronizing frequency doubling signal S2 output; in the time of can preventing that so scan-synchronized signal S1 from not importing, because of the electromagnetic interference (EMI) of peripheral circuit produces the synchronizing frequency doubling signal S2 of trace and the misoperation of reverse sync frequency-doubled signal S6.
In synchronizing frequency doubling signal generating device 20, this first integral unit 202 is to connect a capacitor by a resistor in series.This second integral unit 204 is to connect a capacitor by a resistor in series.This integration switch unit 201 is to be connected to form by at least one MOS transistor.The frequency of this synchronizing frequency doubling signal S2 is the twice of this scan-synchronized signal S1.
Please cooperate Fig. 5, with reference to figure 6, Fig. 6 is the synchronizing frequency doubling signal generating device circuit diagram of preferred embodiment of the present invention.In Fig. 6, integration switch unit 201 is to be connected to form by MOS transistor Q2, Q3, Q4.First integral unit 202 is to be connected to form by a resistor R 7 capacitor C2 that is connected in series.Second integral unit 204 is to be connected to form by a resistor R 6 capacitor C4 that is connected in series.206 of adder units are made up of two diode D1, D2.
Fig. 7 is the circuit waveform synoptic diagram of Fig. 6.Cooperate Fig. 7, with reference to figure 6, synchronizing frequency doubling signal generating device 20 its circuit working principles are as follows: integration switch unit 201 is controlled by the scan-synchronized signal S1 of a fixed frequency square wave, when time t0 arrives t1, scan-synchronized signal S1 is high levle (high), MOS transistor Q3 conducting (ON) in the integration switch unit 201, MOS transistor Q2 are by (OFF), MOS transistor Q4 conducting (ON), this moment, voltage source V CC was the 7 pairs of capacitor C2 chargings of resistor R in first integral unit 202, and went up to such an extent that this first integral signal S3 exports in capacitor C2.And because the conducting (ON) of MOS transistor Q4, cause that capacitor C4 discharges in the second integral unit 204, make that the second integral signal S4 on the capacitor C4 is a zero potential.
As time t1 during to t2, scan-synchronized signal S1 is low level (low), MOS transistor Q3 in the integration switch unit 201 ends (OFF) by (OFF), MOS transistor Q2 conducting (ON), MOS transistor Q4, at this moment, voltage source V CC is the 6 pairs of capacitor C4 chargings of resistor R in second integral unit 204, and goes up to such an extent that this second integral signal S4 exports in capacitor C4.And because the conducting (ON) of MOS transistor Q2, cause that capacitor C2 discharges in the first integral unit 202, make that the first integral signal S3 on the capacitor C2 is a zero potential.
Again with reference to figure 6, synchronizing frequency doubling signal S2 can be again through a phase inverter 207 to produce a reverse sync frequency-doubled signal S6, reverse sync frequency-doubled signal S6 is behind commutation diode D2, the oscillator (indicating) that offers in the PWM unit 22 uses.Moreover; when system does not have scan-synchronized signal S1 to produce; connect the protected location 209 that resistor R 2, R10, R11 and capacitor C1 form by comparator C OMP, promptly can produce a negative potential and offer phase inverter 207, be output as zero (being low level LOW) in order to force it.
In sum, the invention provides a kind of synchronizing frequency doubling signal generating device, be used in the liquid crystal display systems, the scan-synchronized signal in the employing system produces synchronizing frequency doubling signal, to light a lamp as liquid crystal display systems or the light modulation use.The difference frequency that pulse-width modulation produced in can the elimination system of the present invention simultaneously disturbs, and it has circuit advantage simple and with low cost.Simultaneously, the present invention can obtain preferable synchronous regime, and does not have the generation of jitter phenomenon.
The above, only be the detailed description of one the specific embodiment of the best of the present invention and graphic, feature of the present invention is not limited thereto, be not in order to restriction the present invention, all scopes of the present invention should be as the criterion with claim, and all closing in the embodiment of the spirit variation similar with it of claim of the present invention all should be contained in the category of the present invention, anyly be familiar with this skill person in the field of the invention, can think easily and variation or modify the claim that all can be encompassed in following this case.
Claims (12)
1. a synchronizing frequency doubling signal generating device is used in the liquid crystal display systems, is one scan synchronizing signal in the receiving system, output one synchronous frequency-doubled signal uses to system, disturb to reach the difference frequency that pulse-width modulation was produced in synchronous light modulation and the elimination system, it is characterized in that, include:
One integration switch unit is controlled by this scan-synchronized signal, and carries out change action;
One first integral unit is connected in this integration switch unit, carries out integral operation when this scan-synchronized signal of high levle, to export a first integral signal;
One second integral unit is connected in this integration switch unit, carries out integral operation when this scan-synchronized signal of low level, to export a second integral signal;
One adder unit is connected in this first integral unit and this second integral unit, is to add up this first integral signal and this second integral signal, in order to export a frequency multiplication modulating signal; And
One comparing unit is connected in this adder unit, is relatively this a frequency multiplication modulating signal and a reference signal, in order to export this synchronizing frequency doubling signal.
2. synchronizing frequency doubling signal generating device as claimed in claim 1 is characterized in that, further includes a phase inverter and is connected in this comparing unit, and this phase inverter receives this synchronizing frequency doubling signal to produce reverse this synchronizing frequency doubling signal output.
3. synchronizing frequency doubling signal generating device as claimed in claim 2 is characterized in that, further includes a protected location and is connected in this integration switch unit and this phase inverter, when this scan-synchronized signal stops, in order to stop this reverse sync frequency-doubled signal output.
4. synchronizing frequency doubling signal generating device as claimed in claim 1 is characterized in that, this first integral unit is to connect a capacitor by a resistor in series.
5. synchronizing frequency doubling signal generating device as claimed in claim 1 is characterized in that, this second integral unit is to connect a capacitor by a resistor in series.
6. synchronizing frequency doubling signal generating device as claimed in claim 1 is characterized in that, this integration switch unit is to be connected to form by at least one MOS transistor.
7. synchronizing frequency doubling signal generating device as claimed in claim 1 is characterized in that, the frequency of this synchronizing frequency doubling signal is the twice of this scan-synchronized signal.
8. a synchronizing frequency doubling signal production method is used in the liquid crystal display systems, is one scan synchronizing signal in the disposal system, to produce a synchronous frequency-doubled signal, being used for the difference frequency that pulse-width modulation produced in synchronous light modulation and the elimination system disturbs, and it is characterized in that, includes:
Carry out the integral operation first time, when this scan-synchronized signal is in high levle;
Carry out the integral operation second time, when this scan-synchronized signal is in low level;
Add up for the first time the result with the integral operation second time, to produce the integrated signal that a frequency is higher than this scan-synchronized signal; And
This integrated signal of comparison operation and a reference signal are to produce this synchronizing frequency doubling signal.
9. synchronizing frequency doubling signal production method as claimed in claim 8 is characterized in that, when carrying out integral operation second time step, the scan-synchronized signal of low level can be reversed earlier becomes high levels scan-synchronized signal, and the beginning is carried out the integral operation second time.
10. synchronizing frequency doubling signal production method as claimed in claim 8 is characterized in that, when this scan-synchronized signal did not produce, a protected location can be controlled the output that stops this synchronizing frequency doubling signal.
11. synchronizing frequency doubling signal production method as claimed in claim 8 is characterized in that, carries out in the integral operation first time step, integral operation for the first time is to see through a resistor by a voltage source one electric capacity is charged and to reach.
12. synchronizing frequency doubling signal production method as claimed in claim 8 is characterized in that, carries out in the integral operation second time step, integral operation for the second time is to see through a resistor by a voltage source one electric capacity is charged and to reach.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510123657 CN1967652A (en) | 2005-11-18 | 2005-11-18 | Synchronizing frequency doubling signal generating device and method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510123657 CN1967652A (en) | 2005-11-18 | 2005-11-18 | Synchronizing frequency doubling signal generating device and method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102595713A (en) * | 2012-01-19 | 2012-07-18 | 东南大学 | Frequency-doubling light regulating controller |
| CN102932981A (en) * | 2011-08-11 | 2013-02-13 | 原景科技股份有限公司 | Dimming device and signal adjustment device thereof |
| CN109526091A (en) * | 2017-09-20 | 2019-03-26 | 昱京能源科技股份有限公司 | Dimming control system |
| CN112927648A (en) * | 2019-12-06 | 2021-06-08 | 西安诺瓦星云科技股份有限公司 | Display control method and device, module control card and LED display screen |
-
2005
- 2005-11-18 CN CN 200510123657 patent/CN1967652A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102932981A (en) * | 2011-08-11 | 2013-02-13 | 原景科技股份有限公司 | Dimming device and signal adjustment device thereof |
| CN102932981B (en) * | 2011-08-11 | 2016-01-20 | 原景科技股份有限公司 | Light modulating device and sig-nal-conditioning unit thereof |
| CN102595713A (en) * | 2012-01-19 | 2012-07-18 | 东南大学 | Frequency-doubling light regulating controller |
| CN102595713B (en) * | 2012-01-19 | 2014-08-13 | 东南大学 | Frequency-doubling light regulating controller |
| CN109526091A (en) * | 2017-09-20 | 2019-03-26 | 昱京能源科技股份有限公司 | Dimming control system |
| CN109526091B (en) * | 2017-09-20 | 2021-02-19 | 昱京能源科技股份有限公司 | Dimming control system |
| CN112927648A (en) * | 2019-12-06 | 2021-06-08 | 西安诺瓦星云科技股份有限公司 | Display control method and device, module control card and LED display screen |
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