CN100593128C - Liquid crystal display having static noise eliminator - Google Patents
Liquid crystal display having static noise eliminator Download PDFInfo
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- CN100593128C CN100593128C CN200710181667A CN200710181667A CN100593128C CN 100593128 C CN100593128 C CN 100593128C CN 200710181667 A CN200710181667 A CN 200710181667A CN 200710181667 A CN200710181667 A CN 200710181667A CN 100593128 C CN100593128 C CN 100593128C
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- static noise
- lcd
- electrically connected
- voltage
- eliminating device
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Abstract
The invention discloses an LCD having a static noise eliminating device which can eliminate the static noise of at least one loudspeaker on the LCD. A frequency converter adjusts brightness of a luminous tube on an LCD panel by a work cycle control method. In the work cycle control method, an output voltage of power supply equipment is caused to generate continuous waves such that a voltage supplied to a sound source amplifier is unstable. When volume of the loudspeaker is turned to very low or no music is output, the loudspeaker can generate the noise due to unstable voltage of the sound source amplifier. The static noise eliminating device is arranged between the power supply equipment and the sound source amplifier, which can provide a stable output voltage to the sound source amplifierto eliminate the static noise of the loudspeaker on the LCD.
Description
Technical field
The invention relates to the technical field that a kind of noise is eliminated, refer to a kind of static noise eliminating device of LCD especially.
Background technology
Fig. 1 is the calcspar of a known LCD 100.The power supply unit 110 of these LCD 100 inside provides 5V and two groups of power supplys of 24V, wherein 5V is a power supply of supplying with integrated circuit (IC) chip (ICchip), 24V supplies with the fluorescent tube 131 of frequency converter (Inverter) 120 in order to driving display panels 130, and sound source amplifier 140 is sounded in order to promote loudspeaker 150.
Because the light source of the shown picture of LCD panel is the fluorescent tube 131 that comes from display panels 130 inside.And this fluorescent tube 131 is installed on the back side of panel so be referred to as (Backlight) backlight.By adjusting bright-dark degree backlight, the control that just can reach the image brilliance on the panel.
The method of being adjusted light and shade backlight by the output current of frequency converter 120 can be divided into frequency control, amplitude control and three kinds of control methods of work period control.
Control method for frequency is to be applicable to that fluorescent tube 131 is the LCD panel of cold-cathode tube (being CCFL), and its load is capacitive character, so high more its load current of frequency is big more.Fig. 2 is the circuit diagram of a known frequency converter 120.In control method for frequency, its modulation frequency cannot be between audio standard value (for example: below the 20kHz), otherwise people's ear can be heard insufferable noise.The frequency of frequency converter 120 employings at present is about one of them fixed frequency of 50kHz-60kHz.When frequency was adjustable type, 120 need of frequency converter added other protection loop in addition in order to avoid the phase place error takes place when adjusting, and this will cause the too high competitive power that loses of cost.
The amplitude control method is to utilize frequency converter 120 to be output as sine wave, and this sine wave amplitude size is a magnitude of voltage, to adjust light and shade backlight.Regulate the amplitude size and belong to Linear Control, that is the power capacity of the driving crystal of frequency converter inside must be very big, therefore the heat rejection in the time of just being enough to deal with the amplitude minimizing can cause cost to rise and cause producer to adopt with the temperature rise puzzlement.
Fig. 3 is the synoptic diagram of known work periodic Control method.Please in the lump with reference to figure 1, represent when equaling 100% that when the work period (duty cycle) frequency converter 120 outputs are that continuity is not interrupted, this moment, backlight illumination was the brightest.Otherwise the work period, more little then backlight illumination was weak more.For example the work period equals at 0.5 o'clock, and the output of expression frequency converter 120 is intermittences, and 50% cycle belongs to conducting (ON), and 50% cycle belonged to not conducting (OFF) in addition.Therefore the cycle that ON and OFF combined must be very short, in order to avoid human eye perceives goes out to have scintillation.Be generally 5ms-2.5ms this cycle length, is about 200Hz-400Hz.In work cycle control method, be to adopt the ON or the OFF of a miniwatt crystal control input power supply (Vcc=24V) to get final product, so cost is very cheap acceptable to all.
When above-mentioned work cycle control method is adopted in the adjustment backlight of LCD 100, though low price and volume are little, sound interference can take place.That is in the control of the work period of above-mentioned 2.5ms-5ms, cycle in conducting makes power supply unit 110 become heavy duty because of bright lamp backlight, cause the supply voltage (Vcc=24V) of sound source amplifier 140 that the about 0.1V of slight decline is arranged, and make power supply unit 110 become underloading because of light-off backlight in the cycle of not conducting, cause the supply voltage of sound source amplifier 140 to recover normal, promptly do not have pressure drop, be subjected to the oscillogram that inverter current disturbs as the supply voltage of Fig. 4 known sound case source amplifier and illustrate.
Fig. 5 is the application circuit of sound source amplifier 140.This sound source amplifier 140 is TDA 8932 amplifiers that Philip (Philips) company produces.As shown in Figure 5, when above-mentioned Vcc had the 0.1V change, the terminal voltage of commissure (coupling) capacitor (1000uF/35V) 141 of serial connection loudspeaker 150 will and then change.If loudspeaker 150 have music output and power more than 1W, so the listener can not hear the noise that commissure capacitor 141 is produced owing to there is music to export so.If but volume transfer very for a short time or do not have the situation of music output, the user will recognize the noise of the 200Hz-400Hz that commissure capacitor 141 produced, this noise is that commissure capacitor 141 its electric current when discharging and recharging sends by the loudspeaker voice coil loudspeaker voice coil.Hence one can see that, and known technology still has many shortcomings and necessity of being improved is arranged.
Summary of the invention
The objective of the invention is is providing a kind of static noise eliminating device of LCD, so that a sound source amplifier stable power to be provided, and eliminates the caused noise of variation in voltage effectively.
Another object of the present invention is in that a kind of LCD with static noise eliminating device is provided, to eliminate the static noise of at least one loudspeaker on this LCD.
According to a characteristic of the present invention, the present invention is the static noise eliminating device that proposes a kind of LCD, be in order to eliminating the static noise of at least one loudspeaker on this LCD, this static noise eliminating device comprises an input end, a mu balanced circuit, a current amplifier and a bypass resistance.This input end is in order to receive an input voltage; This mu balanced circuit is electrically connected to this input end, so that this input voltage is carried out voltage stabilizing work, and produces a drive current (about 1mA); This current amplifier is electrically connected to this mu balanced circuit, so that this drive current is amplified (about 50mA), this amplified current is provided to one in order to drive the sound source amplifier of these at least one loudspeaker, in order to the voice output below about 1W to be provided; This bypass resistance is electrically connected to this input end and this current amplifier, to be output as when high-power when these at least one loudspeaker, the electric current of this input voltage (about 0.05A-1A) directly flow through this bypass resistance and this sound source amplifier that arrives are in order to provide the voice output of about 1W-10W.
According to another characteristic of the present invention, the present invention proposes a kind of LCD with static noise eliminating device, be the static noise that can eliminate at least one loudspeaker on this LCD, this LCD comprises a display panels, a fluorescent tube, a frequency converter, a power supply unit, a static noise eliminating device and a sound source amplifier.This display panels is in order to show image.This fluorescent tube is electrically connected to this display panels, by the bright-dark degree that adjusts this fluorescent tube, to control the image brilliance on this display panels.This frequency converter is electrically connected to this fluorescent tube, and this frequency converter is adjusted the bright-dark degree of this fluorescent tube by its output current.This power supply unit is electrically connected to this frequency converter, to provide one first voltage to this frequency converter.This static noise eliminating device is electrically connected to this power supply unit, and it receives this first voltage, and this first voltage is carried out voltage stabilizing work, and produces a regulated output voltage.This sound source amplifier is electrically connected to this static noise eliminating device, receiving this regulated output voltage, and receives a sound source signal, to drive at least one loudspeaker.
Description of drawings
Below be by particular specific embodiment explanation embodiments of the present invention, make this invention technical field tool know that usually the knowledgeable can understand other advantage of the present invention and effect easily by content and accompanying drawing that this instructions disclosed, wherein:
Fig. 1 is the calcspar of a known LCD.
Fig. 2 is the circuit diagram of a known frequency converter
Fig. 3 is the oscillogram that known frequency converter utilizes work period control brightness.
Fig. 4 is that the supply voltage of known sound case source amplifier is subjected to the oscillogram that inverter current disturbs.
Fig. 5 is the application circuit of known sound case source amplifier.
Fig. 6 is the calcspar that the present invention has the LCD of static noise eliminating device.
Fig. 7 is the circuit diagram of static noise eliminating device of the present invention, and is output as the working current path profile when high-power.
Fig. 8 is the working current path profile of the present invention when at least one loudspeaker are output as miniwatt.
Embodiment
Fig. 6 is the calcspar that the present invention has the LCD of static noise eliminating device, be the static noise that can eliminate at least one loudspeaker on this LCD, this LCD comprises a display panels 130, a fluorescent tube 131, a frequency converter 630, a power supply unit 640, a static noise eliminating device 650, a sound source amplifier 660 and at least one loudspeaker 670.
This display panels 610 is in order to show image.This fluorescent tube 620 is electrically connected to this display panels 610, by the bright-dark degree that adjusts this fluorescent tube 620, to control the image brilliance on this display panels 610.
This frequency converter 630 is electrically connected to this fluorescent tube 620, and this frequency converter 630 is adjusted the bright-dark degree of this fluorescent tube 620 by its output current.This power supply unit 640 is electrically connected to this frequency converter 630, to provide one first voltage to this frequency converter 630.This first voltage is preferably 24 volts.This power supply unit 640 is also exported one second voltage simultaneously, and so that the integrated circuit (IC) of this second voltage to this LCD to be provided, this second voltage is preferably 5 volts.
This static noise eliminating device 650 is electrically connected to this power supply unit 640, and it receives this first voltage, and this first voltage is carried out voltage stabilizing work, and produces a regulated output voltage.
This sound source amplifier 660 is electrically connected to this static noise eliminating device 650, receiving this regulated output voltage, and receives a sound source signal, to drive these at least one loudspeaker 670.
Fig. 7 is the circuit diagram of static noise eliminating device 650 of the present invention, and also please in the lump simultaneously with reference to figure 6, this static noise eliminating device 650 comprises an input end 710, a mu balanced circuit 720, a current amplifier 730 and a bypass resistance 740.
This input end 710 is in order to receive this first voltage Vin.This mu balanced circuit 720 is electrically connected to this input end 710, this first voltage Vin being carried out voltage stabilizing work, and produces a drive current.
This current amplifier 730 is electrically connected to this mu balanced circuit 720, so that this drive current is amplified, provide to this sound source amplifier 660 with the drive current that will amplify, with when these at least one loudspeaker 670 are output as miniwatt, the electric current of this first voltage flow through this current amplifier 730 and this sound source amplifier 660 that arrives.This bypass resistance 740 is electrically connected to this input end 710 and this current amplifier 730, to be output as when high-power when these at least one loudspeaker 670, and the electric current of this first voltage directly flow through this bypass resistance 740 and this sound source amplifier 660 that arrives.This mu balanced circuit 720 is formed (or install a Zener diode 723 additional more can increase effect) by a resistance 721, an electric capacity 722.This current amplifier 730 is npn transistors.Be described in detail as follows, promptly these resistance 721 1 ends are electrically connected to this input end 710, and its other end is electrically connected to the base stage (723 of Zener diodes are in parallel with electric capacity 722 if any installing additional) of anode and this npn transistor 730 of this electric capacity 722.The collection utmost point of this npn transistor 730 is electrically connected to this input end 710, and its emitter-base bandgap grading is electrically connected to this sound source amplifier 660 via an output terminal 750.
What need be illustrated is that above-mentioned mu balanced circuit 720 is to be integrated into (figure does not illustrate) in the integrated regulator with current amplifier 730.
Wherein, this bypass resistance 740 is made up of one first diode 741 and one second diode 742.Be described in detail as follows, promptly the anode of this first diode 741 is electrically connected to this input end 710, and its negative terminal is electrically connected to this second diode, 742 anodes, and the negative terminal of this second diode 742 even is connected to this sound source amplifier 660 via this output terminal 750.
As shown in Figure 7, when these at least one loudspeaker 670 are output as when high-power, the electric current of this first voltage directly flow through this bypass resistance 740 and this sound source amplifier 660 that arrives.When these at least one loudspeaker 670 are output as when high-power, because of transistorized collection (Collector)-penetrating (Emitter) extreme pressure falls (V
CE) greater than twice diode pressure drop (V forward
F), that is V
CE＞2V
F, make electric current change and walk this bypass resistance 740 that two diodes are connected, shown in the dotted line of Fig. 7.So V
CEThe pressure drop meeting be limited in 2V
F, i.e. V
CE≤ 2V
F, 730 circulations of expression transistor sub-fraction electric current, most electric current then passes through bypass resistance 740.
When these at least one loudspeaker 670 are output as miniwatt, the electric current of this first voltage flow through this current amplifier 730 and this sound source amplifier 660 that arrives.When these at least one loudspeaker 670 were output as miniwatt, electric current was through the collection (Collector) of npn transistor 730-penetrate (Emitter) utmost point, as Fig. 8 dotted line shown in.This circuit is actually a kind of stable-pressure device, and this first voltage Vin is earlier through resistance 7
21, the about 1mA of its electric current of voltage regulation after electric capacity 722 voltage stabilizings amplifies its electric current of voltage regulation to the 50mA through npn transistor 730 again, and wherein, resistance 721 is capacitor for filter for step-down current limliting resistor, electric capacity 722.(Zener diode 723 is the voltage stabilizing diode).
As shown in the above description, the caused souffle problem of variation in voltage that the present invention is directed to Fig. 4 gives effective processing, that is increases this static noise eliminating device 650 between the Vcc of sound source amplifier 660 and power supply unit 640.By the static noise eliminating device of LCD of the present invention, can provide sound source amplifier 660 stable power the static noise eliminating device on the display 650, and eliminate the caused noise of variation in voltage effectively.
The foregoing description only is to give an example for convenience of description, and the interest field that the present invention advocated is from should be with described being as the criterion of scope of the claim applied for a patent, but not only limits to the foregoing description.
Claims (8)
1. the LCD with static noise eliminating device is the static noise that can eliminate at least one loudspeaker on this LCD, it is characterized in that, this LCD comprises:
One display panels is in order to show image;
One fluorescent tube is electrically connected to this display panels, by the bright-dark degree that adjusts this fluorescent tube, to control the image brilliance on this display panels;
One frequency converter is electrically connected to this fluorescent tube, and this frequency converter is adjusted the bright-dark degree of this fluorescent tube by its output current;
One power supply unit is electrically connected to this frequency converter, to provide one first voltage to this frequency converter;
One static noise eliminating device is electrically connected to this power supply unit, and it receives this first voltage, and this first voltage is carried out voltage stabilizing work, and produces a regulated output voltage; And
One sound source amplifier is electrically connected to this static noise eliminating device, receiving this regulated output voltage, and receives a sound source signal, to drive at least one loudspeaker.
2. the LCD with static noise eliminating device as claimed in claim 1 is in order to eliminating the static noise of at least one loudspeaker on this LCD, it is characterized in that, this static noise eliminating device comprises:
One input end is in order to receive this first voltage;
One mu balanced circuit is electrically connected to this input end, so that this first voltage is carried out voltage stabilizing work, and produces a drive current;
One current amplifier is electrically connected to this mu balanced circuit, so that this drive current is amplified, this amplified current is provided to one in order to drive a sound source amplifier of these at least one loudspeaker; And
One bypass resistance is electrically connected to this input end and this current amplifier, to be output as when high-power when these at least one loudspeaker, and the electric current of this first voltage directly flow through this bypass resistance and this sound source amplifier that arrives.
3. the LCD with static noise eliminating device as claimed in claim 2 is characterized in that, wherein, when these at least one loudspeaker are output as miniwatt, the electric current of this first voltage flow through this current amplifier and this sound source amplifier that arrives.
4. the LCD with static noise eliminating device as claimed in claim 3 is characterized in that, wherein, this mu balanced circuit is made up of a resistance, an electric capacity at least, and this current amplifier is a npn transistor.
5. the LCD with static noise eliminating device as claimed in claim 3 is characterized in that, wherein, this mu balanced circuit and current amplifier can be integrated in the integrated regulator.
6. the LCD with static noise eliminating device as claimed in claim 2 is characterized in that, wherein, this bypass resistance is made up of one first diode and one second diode.
7. the LCD with static noise eliminating device as claimed in claim 4 is characterized in that, wherein, the transistorized collection utmost point of this npn is electrically connected to this input end, and its emitter-base bandgap grading is electrically connected to this sound source amplifier.
8. the LCD with static noise eliminating device as claimed in claim 6, it is characterized in that, wherein, the anode of this first diode is electrically connected to this input end, its negative terminal is electrically connected to this second diode anode, and the negative terminal of this second diode is electrically connected to this sound source amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710181667A CN100593128C (en) | 2007-10-22 | 2007-10-22 | Liquid crystal display having static noise eliminator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710181667A CN100593128C (en) | 2007-10-22 | 2007-10-22 | Liquid crystal display having static noise eliminator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101419348A CN101419348A (en) | 2009-04-29 |
| CN100593128C true CN100593128C (en) | 2010-03-03 |
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ID=40630210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200710181667A Expired - Fee Related CN100593128C (en) | 2007-10-22 | 2007-10-22 | Liquid crystal display having static noise eliminator |
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| Country | Link |
|---|---|
| CN (1) | CN100593128C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105744187A (en) * | 2016-04-06 | 2016-07-06 | 青岛海信电器股份有限公司 | Display device and liquid crystal display television |
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- 2007-10-22 CN CN200710181667A patent/CN100593128C/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| CN101419348A (en) | 2009-04-29 |
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Granted publication date: 20100303 Termination date: 20131022 |