CN101728967A - Frequency converter and method for controlling output frequency of frequency converter - Google Patents
Frequency converter and method for controlling output frequency of frequency converter Download PDFInfo
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- CN101728967A CN101728967A CN200810167538A CN200810167538A CN101728967A CN 101728967 A CN101728967 A CN 101728967A CN 200810167538 A CN200810167538 A CN 200810167538A CN 200810167538 A CN200810167538 A CN 200810167538A CN 101728967 A CN101728967 A CN 101728967A
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Abstract
The invention provides a frequency converter, comprising a counter, a pulse width adjusting device, a central controller and a power converting unit. The counter is used for receiving a frame switching signal to generate a frame counting signal; the pulse width adjusting device is coupled with the counter and used for selecting a special frequency from a plurality of preset frequencies according to the frame counting signal to generate an adjusted signal with the special frequency; the central controller is coupled with the pulse width adjusting device and used for generating a processed signal according to the adjusted signal; and the power converting unit is coupled with the central controller and used for generating an output signal according to the processed signal.
Description
Technical field
The relevant power switching mechanism of the present invention, refer to especially a kind of can be according to a frame switching signal with decision frequency converter of output signal frequency and the method that is used for controlling this frequency converter output frequency.
Background technology
For using the LCD of direct type backlight module, because lamp tube ends is high drive (about 1000 volts), therefore electromagnetic interference (the Electro-MagneticInterference that frequency converter and fluorescent tube produced, EMI) can impact display pannel, and make display frame the phenomenon of ripples line (waving) occur.Generally speaking, the horizontal stripe of ripples line for moving up and down, and the position that the ripples line is occurred on display pannel is relevant with the output frequency of frequency converter (that is driving frequency of lamp tube ends), if that is the output frequency of frequency converter is a fixed value, then the ripples line can appear at the position of early-fixed on the display pannel, therefore, discovered by the user very easily and cause the low of display quality, in other words, if use the frequency converter of known output fixed frequency to drive fluorescent tube, can cause tangible water ripple phenomenon and have influence on the image display quality.
Summary of the invention
Therefore, one of purpose of the present invention be to provide a kind of can be according to a frame switching signal with the frequency converter of decision output frequency and the method that is used for controlling this frequency converter output frequency, to solve the above problems.
According to one embodiment of the invention, it discloses a kind of frequency converter.This frequency converter includes: a counter is used for receiving a frame switching signal (frame switching signal) to produce a frame count signal (frame counting signal); One pulse width modulation device (pulse width modulator) is coupled to this counter, is used for according to this frame count signal from selecting a characteristic frequency to produce signal behind the modulation with this characteristic frequency in a plurality of predeterminated frequencies; One central controller is coupled to this pulse width modulation device, is used for handling the back signal according to signal behind this modulation to produce one; And a power conversion unit, be coupled to this central controller, be used for according to this processing back signal to produce an output signal.
According to one embodiment of the invention, it discloses a kind of method that is used for controlling the output frequency of a frequency converter.This method includes: count a frame switching signal to produce a frame count signal; Has signal behind the modulation of this characteristic frequency according to this frame count signal with generation from selecting a characteristic frequency to carry out pulse width modulation in a plurality of predeterminated frequencies; Handle the back signal according to signal behind this modulation to produce one; And carry out power conversions to produce an output signal according to this processing back signal.
According to the disclosed frequency converter of the present invention and be used for the method for output frequency of control of conversion device, the output frequency of frequency converter can decide according to a frame switching signal, that is the output frequency of frequency converter can change along with the time, therefore in a successive frame, ripples line when each frame shows on the display pannel can not appear at position similar on the panel, therefore under the effect of image equalization, the water ripple phenomenon of display pannel can be more not obvious, that is be difficult for being found by the user, so the image display quality also can improve.
Description of drawings
Fig. 1 is the schematic diagram of a frequency converter of the embodiment of the invention;
Fig. 2 is for describing the operational flowchart of frequency converter shown in Figure 1.
The primary clustering symbol description
100 frequency converters
110 counters
120 pulse width modulation devices
130 central controllers
140 power conversion unit
150 voltage regulation units
Embodiment
Please refer to Fig. 1, Fig. 1 is the schematic diagram of an embodiment of frequency converter 100 of the present invention.As shown in Figure 1, frequency converter 100 includes a counter 110, a pulse width modulation device 120, a central controller 130, a power conversion unit 140 and a voltage regulation unit 150.
Please also refer to Fig. 1 and Fig. 2, Fig. 2 is the operational flowchart of frequency converter 100 shown in Figure 1.If have identical in fact result, the operating procedure of frequency converter 100 is not exceeded with step shown in Figure 2 and execution order.With reference to flow chart shown in Figure 2, the operation of frequency converter 100 is described below:
In step 202, counter 110 receives and counts a frame switching signal SW to produce a frame count signal, by a control board (not illustrating) or other circuit unit is produced, and frame switching signal SW also can be described as arteriogram (start pulse) signal together when wherein frame switching signal SW switched by two frames; Then in step 204, pulse width modulation device 120 according to this frame count signal from selecting a characteristic frequency to produce signal behind the modulation with this characteristic frequency in a plurality of predeterminated frequencies; Afterwards in step 206, central controller 130 according to this modulation after signal, a dim signal, a voltage protecting signal, a current controling signal ... or the like handle the back signal to produce one; At last, in step 208, power conversion unit 140 is coupled to central controller 130, is used for producing an output signal V according to direct voltage after this a processing back signal and the voltage stabilizing
OUT, wherein direct voltage receives a direct current voltage V by voltage regulation unit 150 after this voltage stabilizing
DCProduce and output signal V
OUTFor being used for driving a high-voltage AC signal of fluorescent tube.
In this example, these a plurality of predeterminated frequencies come out by the operating frequency range of frequency converter 100 is selected, and the difference of any two immediate frequencies all equates in these a plurality of predeterminated frequencies, and this difference is all less than 3KHz; In addition, pulse width modulation device 120 is chosen mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies according to this frame count signal with one-period property, and pulse width modulation device 120 produces that the running of signal includes one first operation time period and one second operation time period behind these modulations, and this first operation time period and this second operation time period are the period that is connected with each other; When in this first operation time period, a frequency of signal increases up to this frequency sequentially in these a plurality of predeterminated frequencies behind this modulation | maximum; And when in this second operation time period, this frequency of signal reduces sequentially up to this frequency and is the minimum value in these a plurality of predeterminated frequencies behind this modulation.For making technical characterictic of the present invention clearer and more definite, below will illustrate the running that pulse width modulation device 120 produces signal behind these modulations.
In an embodiment, the operating frequency range of supposing frequency converter 100 is 59KHz-67KHz, therefore, above-mentioned a plurality of predeterminated frequencies are respectively 59KHz, 61KHz, 63KHz, 65KHz, 67KHz, in addition, in the operation of frequency converter 100, when first frame shows, the output signal V of frequency converter 100
OUTThe frequency frequency of signal (that is behind the modulation that pulse width modulation device 120 produced) be 59KHz; When second frame shows, the output signal V of frequency converter 100
OUTFrequency be 61KHz; When the 3rd to the 8th frame shows, the output signal V of frequency converter 100
OUTFrequency be respectively 63KHz, 65KHz, 67KHz, 65KHz, 63KHz, 61KHz; Afterwards, in ensuing frame shows, the output signal V that frequency converter 100 is exported when repeating above-mentioned first frame to the, eight frames and showing
OUT, that is be the output signal V that one-period periodically exports frequency converter 100 with above-mentioned first frame to the, eight frames
OUT
Be noted that, above-mentioned these a plurality of predeterminated frequencies are only as the usefulness of example explanation, the numerical value of these a plurality of predeterminated frequencies and quantity can change to some extent according to designer's consideration, in addition, above-mentioned pulse width modulation device 120 periodically selects this characteristic frequency in these a plurality of predeterminated frequencies mode only is a preferred embodiment, on real the work, pulse width modulation device 120 in addition can be according to this frame count signal in a picked at random mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies, briefly, as long as the output signal V of frequency converter 100
OUTFrequency change to some extent along with this frame count signal, the variation in these designs all should spirit according to the invention and be subordinate to category of the present invention.
Because the position that the ripples line is occurred on display pannel is relevant with the output frequency of frequency converter, if therefore the output frequency of frequency converter 100 changes along with the frame count signal, when each frame shows on display pannel the appearance position of ripples line also inequality, therefore under the influence of the persistence of vision and show image equalization, water ripple phenomenon can be more not obvious.
The simple method of output frequency of concluding above-mentioned frequency converter and being used for the control of conversion device, in the present invention, at first a counter receives a frame switching signal to produce a frame count signal; Then a pulse width modulation device according to this frame count signal from selecting a characteristic frequency to produce signal behind the modulation with this characteristic frequency in a plurality of predeterminated frequencies; Afterwards a central controller according to this modulation after signal handle the back signal to produce one; Last power conversion unit according to this processing back signal to produce an output signal, in addition, this pulse width modulation device according to this frame count signal with one at random or one-period property choose mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies.
In sum, use the water ripple phenomenon that frequency converter of the present invention can reduce display pannel, and then improve the image display quality.
The above only is preferred embodiment of the present invention, and the equalization that Fan Yiben claims are done changes and modifies, and all should belong to covering scope of the present invention.
Claims (12)
1. a frequency converter is characterized in that, includes:
One counter is used for receiving a frame switching signal to produce a frame count signal;
One pulse width modulation device is coupled to this counter, is used for according to this frame count signal from selecting a characteristic frequency to produce signal behind the modulation with this characteristic frequency in a plurality of predeterminated frequencies;
One central controller is coupled to this pulse width modulation device, is used for handling the back signal according to signal behind this modulation to produce one; And
One power conversion unit is coupled to this central controller, is used for according to this processing back signal to produce an output signal.
2. frequency converter as claimed in claim 1 is characterized in that, the difference of any two immediate frequencies all equates in these a plurality of predeterminated frequencies.
3. frequency converter as claimed in claim 1 is characterized in that, the difference of any two immediate frequencies is all less than 3KHz in these a plurality of predeterminated frequencies.
4. frequency converter as claimed in claim 1 is characterized in that, this pulse width modulation device according to this frame count signal in a picked at random mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies.
5. frequency converter as claimed in claim 1 is characterized in that, this pulse width modulation device is chosen mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies according to this frame count signal with one-period property.
6. frequency converter as claimed in claim 5, it is characterized in that, this pulse width modulation device produces that the running of signal includes one first operation time period and one second operation time period behind this modulation, and this first operation time period and this second operation time period are the period that is connected with each other; When in this first operation time period, a frequency of signal increases sequentially up to this frequency and is the maximum in these a plurality of predeterminated frequencies behind this modulation; And when in this second operation time period, this frequency of signal reduces sequentially up to this frequency and is the minimum value in these a plurality of predeterminated frequencies behind this modulation.
7. a method that is used for controlling the output frequency of a frequency converter is characterized in that, includes:
Count a frame switching signal to produce a frame count signal;
Has signal behind the modulation of this characteristic frequency according to this frame count signal with generation from selecting a characteristic frequency to carry out pulse width modulation in a plurality of predeterminated frequencies;
Handle the back signal according to signal behind this modulation to produce one; And carry out power conversions to produce an output signal according to this processing back signal.
8. method as claimed in claim 7 is characterized in that, the difference of any two immediate frequencies all equates in these a plurality of predeterminated frequencies.
9. method as claimed in claim 7 is characterized in that, the difference of any two immediate frequencies is all less than 3KHz in these a plurality of predeterminated frequencies.
10. method as claimed in claim 7 is characterized in that, has from selecting a characteristic frequency to carry out pulse width modulation in a plurality of predeterminated frequencies that the step of signal includes behind the modulation of this characteristic frequency according to this frame count signal with generation:
According to this frame count signal in a picked at random mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies.
11. method as claimed in claim 7 is characterized in that, has from selecting a characteristic frequency to carry out pulse width modulation in a plurality of predeterminated frequencies that the step of signal includes behind the modulation of this characteristic frequency according to this frame count signal with generation:
Choose mode from selecting this characteristic frequency in these a plurality of predeterminated frequencies according to this frame count signal with one-period property.
12. method as claimed in claim 11 is characterized in that, produces that the running of signal includes one first operation time period and one second operation time period behind this modulation, and this first operation time period and this second operation time period are the period that is connected with each other; When in this first operation time period, a frequency of signal increases sequentially up to this frequency and is the maximum in these a plurality of predeterminated frequencies behind this modulation; And when in this second operation time period, this frequency of signal reduces sequentially up to this frequency and is the minimum value in these a plurality of predeterminated frequencies behind this modulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN200810167538A CN101728967A (en) | 2008-10-10 | 2008-10-10 | Frequency converter and method for controlling output frequency of frequency converter |
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| Application Number | Priority Date | Filing Date | Title |
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| CN200810167538A CN101728967A (en) | 2008-10-10 | 2008-10-10 | Frequency converter and method for controlling output frequency of frequency converter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103201938A (en) * | 2010-09-17 | 2013-07-10 | 高通股份有限公司 | Synchronously sampled single bit switch mode power supply |
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2008
- 2008-10-10 CN CN200810167538A patent/CN101728967A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103201938A (en) * | 2010-09-17 | 2013-07-10 | 高通股份有限公司 | Synchronously sampled single bit switch mode power supply |
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Application publication date: 20100609 |