CN101315486B - Backlight control circuit and control method thereof - Google Patents
Backlight control circuit and control method thereof Download PDFInfo
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- CN101315486B CN101315486B CN2007100748099A CN200710074809A CN101315486B CN 101315486 B CN101315486 B CN 101315486B CN 2007100748099 A CN2007100748099 A CN 2007100748099A CN 200710074809 A CN200710074809 A CN 200710074809A CN 101315486 B CN101315486 B CN 101315486B
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Abstract
The invention relates to a backlight control circuit and a control method thereof, wherein the backlight control circuit comprises a backlight lamp, a reversed-phase circuit, a pulse width modulation integrated circuit, a lighting tube identification circuit and a frequency adjustment circuit, wherein the pulse width modulation integrated circuit generates a pulse signal to the reversed-phase circuit; according to the pulse signal, the reversed-phase circuit converts a DC voltage into an AC voltage to drive the backlight lamp; the lighting tube identification circuit identifies the type of the lighting tube of the backlight lamp; and the frequency adjustment circuit adjusts the frequency of the pulse signal generated by the pulse width modulation integrated circuit according to the type of the lighting tube, so that the reversed-phase circuit adjusts the frequency of the AC voltage.
Description
Technical field
The present invention relates to a kind of backlight control circuit and control method thereof.
Background technology
Characteristics such as LCD has frivolous, and low power consumption and radiation are few, and extensively be used in electronic equipments such as display, LCD TV, mobile phone and notebook computer.Because the liquid crystal molecule itself in the LCD is not luminous, so LCD needs to show by the luminous image of realizing of a module backlight.Usually adopt in the module backlight cold cathode ray tube (coldcathode fluorescent lamp, CCLF) or light emitting diode as its luminous light source.
When adopting cold cathode ray tube,, therefore need the backlight control circuit of design specialized, DC voltage is converted into alternating voltage drives this cold cathode ray tube because cold cathode ray tube needs High AC voltage to drive as light source.
Seeing also Fig. 1, is a kind of synoptic diagram of prior art backlight control circuit.This backlight control circuit 100 comprises a pulse-width modulation integrated circuit (Pulse Width Modulation, PWM) 120, one frequency setting circuit 130, a negative circuit (Inverter) 140 and a backlight 150.This backlight 150 is cold cathode ray tubes.The model of this pulse-width modulation integrated circuit 120 is OZ9910.
This pulse-width modulation integrated circuit 120 comprises a frequency setting end 121 and a power end 122.This frequency setting circuit 130 comprises resistance 132 and an electric capacity 131.This frequency setting end 121 is via these electric capacity 131 ground connection.This resistance 132 is connected between this frequency setting end 121 and this power end 122.
Produce a pulse signal during these pulse-width modulation integrated circuit 120 operate as normal to this negative circuit 140, this negative circuit 140 is that an alternating voltage is used for driving this backlight 150 according to this pulse signal with a direct current voltage transitions.The frequency of this pulse signal is by the size decision of this resistance 132 and electric capacity 131, and the frequency of this alternating voltage is consistent with the frequency of this pulse signal.
From the above, the frequency of operation of this backlight 150 (i.e. the frequency of this alternating voltage) is by the frequency decision of this pulse signal, connects therebetween and depends on this resistance 132 and electric capacity 131.The relational expression of the frequency of this pulse signal and this resistance 132 and electric capacity 131 is as follows:
Wherein, f
OpBe the frequency of this pulse signal, unit is kHZ; R
CTBe the resistance of this resistance 132, unit is k Ω; C
CTBe the capacity of this electric capacity 131, unit is pF.
For the cold cathode ray tube of different size, its frequency optimum traffic difference, therefore, and when using this pulse-width modulation integrated circuit 120, according to the size of the cold cathode ray tube that it drove, the corresponding resistance of this resistance 132 and the capacity of electric capacity 131 set.
Yet, be difficult for change because this frequency of operation is set the back, make this backlight control circuit 100 only be suitable for a kind of cold cathode ray tube of size, if drive the cold cathode ray tube of other size or model, then may make cold cathode ray tube can not be operated in frequency optimum traffic, luminescence efficiency is lower.
Summary of the invention
For solving the lower problem of backlight control circuit luminescence efficiency in the prior art, be necessary the backlight control circuit that provides a kind of luminescence efficiency higher.
Also be necessary to provide the control method of the higher backlight control circuit of a kind of luminescence efficiency.
A kind of backlight control circuit, it comprises a backlight, a negative circuit, a pulse-width modulation integrated circuit, a fluorescent tube identification circuit and a frequency regulating circuit; Wherein, this pulse-width modulation integrated circuit produces a pulse signal to this negative circuit, this negative circuit is that an alternating voltage drives this backlight according to this pulse signal with a direct current voltage transitions, this fluorescent tube identification circuit is discerned the lamp type of this backlight, this frequency regulating circuit is adjusted the frequency of the pulse signal that this pulse-width modulation integrated circuit produces according to this lamp type, thereby this negative circuit is adjusted the frequency of this alternating voltage.
A kind of control method of backlight control circuit, this backlight control circuit comprises a backlight, one negative circuit and a pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit produces a pulse signal to this negative circuit, this negative circuit is that an alternating voltage drives this backlight according to this pulse signal with a direct current voltage transitions, and this control method comprises the steps:
(a) provide an alternating voltage to drive this backlight;
(b) discern the lamp type of this backlight; With
(c) adjust the frequency of this alternating voltage according to this lamp type.
With respect to prior art, in this backlight control circuit and the control method thereof, lamp type by discerning this backlight and according to lamp type adjustment drives the frequency of the alternating voltage of this backlight, make this backlight be operated in frequency optimum traffic, luminescence efficiency is higher.
Description of drawings
Fig. 1 is a kind of synoptic diagram of prior art backlight control circuit.
Fig. 2 is the synoptic diagram of backlight control circuit one better embodiment of the present invention.
Fig. 3 is the part synoptic diagram of backlight control circuit shown in Figure 2.
Embodiment
Seeing also Fig. 2, is the synoptic diagram of backlight control circuit one better embodiment of the present invention.This backlight control circuit 200 comprises a backlight 250, a negative circuit 240, a pulse-width modulation integrated circuit 220, a fluorescent tube identification circuit 260 and a frequency regulating circuit 230.This backlight 250 is cold cathode ray tubes.The model of this pulse-width modulation integrated circuit 220 is OZ9910.
This frequency regulating circuit 230 comprises a digital variable resistance 232, an electric capacity 231, a look-up table 234 and a code translator 235.Seeing also Fig. 3, is the synoptic diagram of this look-up table 234.The a plurality of lamp type of this look-up table 234 storages (as: 1,2 ..., the n type) and represent the frequency optimum traffic of the type fluorescent tube binary command (as: 11100111,11100000 ..., 11111111).This pulse-width modulation integrated circuit 220 comprises a frequency setting end 221 and a power end 222, and this frequency setting end 221 is via these electric capacity 231 ground connection.
This digital variable resistance 232 comprises a plurality of resistance 2321 and a plurality of on-off element 2322.Each on-off element 2322 comprises one first conduction terminal 1, one second conduction terminal 2 and a control end 3.These a plurality of resistance 2321 constitute a series connection branch road, one end of this series arm (not indicating) connects this power end 222, the other end (not indicating) connects this frequency setting end 221 via second conduction terminal 2, first conduction terminal 1 of an on-off element 2322, and the circuit node 2323 that every adjacent two resistance are 2321 connects this frequency setting end 221 via second conduction terminal 2, first conduction terminal 1 of an on-off element 2322.This code translator 235 comprises a plurality of output terminals (not indicating), the corresponding control end 3 that connects an on-off element 2322 of each output terminal.
During these backlight control circuit 200 work, this digital variable resistance 232 tools one initial resistance.
The principle of work of this backlight control circuit 200 is as follows:
This pulse-width modulation integrated circuit 220 produces a pulse signal to this negative circuit 240 according to initial resistance and this electric capacity 231 of this digital variable resistance 232.
This negative circuit 240 is that an alternating voltage drives this backlight 250 according to this pulse signal with a direct current voltage transitions, and this backlight 250 starts and be luminous.
Voltage and current after this this backlight 250 of fluorescent tube identification circuit 260 samplings starts in a period of time, and according to this change in voltage and electrorheological divide the lamp type of separating out this backlight (as: 1,2 ..., the n type, be assumed to be 1 type), output represents the signal of this lamp type (1 type) to this look-up table 234.
This look-up table 234 finds out the binary command (11100111) of the corresponding frequency optimum traffic of the type fluorescent tube (1 type) according to the signal of this lamp type (1 type), and exports this binary command (11100111) to this code translator 235.
These these binary commands of code translator 235 deciphers (11100111), the resistance of this digital variable resistance 232 is adjusted in the conducting or the not conducting of a plurality of on-off elements 2322 by controlling this digital variable resistance 232.
This pulse-width modulation integrated circuit 220 is according to the frequency of the pulse signal of the resistance adjustment output of this digital variable resistance 232.This negative circuit 240 is according to the frequency of the alternating voltage of adjusted pulse signal adjustment output, thereby this backlight 250 is operated in frequency optimum traffic.
With respect to prior art, voltage and current after the fluorescent tube identification circuit 260 of this backlight control circuit 200 starts according to this backlight 250 in a period of time, discern the lamp type of this backlight 250, this frequency regulating circuit 230 is adjusted the frequency of the pulse signal of these PM integrated circuit 220 outputs according to this lamp type, and then this negative circuit 240 is adjusted the frequency of the alternating voltage of output, make this backlight 250 be operated in frequency optimum traffic, luminescence efficiency is higher.
It is described that backlight control circuit of the present invention and control method thereof are not limited to above-mentioned embodiment, as: when adopting different PM integrated circuit 220, its connected mode with this frequency regulating circuit 230 is different, as when adopting this PM integrated circuit 220 to adopt QZ960, its two ends that are connected with frequency setting circuit 230 are respectively first frequency and set end and second frequency setting end, and this first frequency is set end via these electric capacity 231 ground connection, and this second frequency is set end via these digital variable resistance 232 ground connection.
Claims (10)
1. backlight control circuit, it comprises a backlight, one negative circuit and a pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit produces a pulse signal to this negative circuit, this negative circuit is that an alternating voltage drives this backlight according to this pulse signal with a direct current voltage transitions, it is characterized in that: this backlight control circuit also comprises a fluorescent tube identification circuit and a frequency regulating circuit, this fluorescent tube identification circuit is discerned the lamp type of this backlight, this frequency regulating circuit is adjusted the frequency of the pulse signal that this pulse-width modulation integrated circuit produces according to this lamp type, thereby this negative circuit is adjusted the frequency of this alternating voltage.
2. backlight control circuit as claimed in claim 1 is characterized in that: this fluorescent tube identification circuit is discerned the lamp type of this backlight according to the voltage and current in a period of time after this backlight startup.
3. backlight control circuit as claimed in claim 2, it is characterized in that: this frequency regulating circuit comprises an electric capacity, a variable resistor, a look-up table and a code translator, this pulse-width modulation integrated circuit comprises a power end and a frequency setting end, this power end connects this frequency setting end via this variable resistor, this frequency setting end is via this capacity earth, this look-up table is exported the instruction of this lamp type correspondence to this code translator according to this lamp type, this code translator is adjusted this variable-resistance resistance according to this instruction.
4. backlight control circuit as claimed in claim 3 is characterized in that: a plurality of lamp type of this look-up table stores and the binary command of representing the frequency optimum traffic of the type fluorescent tube, the instruction that this look-up table outputs to this code translator is a binary command.
5. backlight control circuit as claimed in claim 3, it is characterized in that: this variable resistor is a digital variable resistance, it comprises a plurality of resistance and a plurality of on-off element, each on-off element comprises one first conduction terminal, one second conduction terminal and a control end, these a plurality of resistance constitute a series connection branch road, one end of this series arm connects this power end, the other end is via second conduction terminal of an on-off element, first conduction terminal connects this frequency setting end, node between every adjacent two resistance is via second conduction terminal of an on-off element, first conduction terminal connects this frequency setting end, and the control end of these a plurality of on-off elements connects each output terminal of this code translator respectively.
6. backlight control circuit as claimed in claim 1 is characterized in that: this backlight is a cold cathode ray tube.
7. the control method of a backlight control circuit, this backlight control circuit comprises a backlight, one negative circuit and a pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit produces a pulse signal to this negative circuit, this negative circuit is that an alternating voltage drives this backlight according to this pulse signal with a direct current voltage transitions, and this control method comprises the steps:
(a) provide an alternating voltage to drive this backlight;
(b) discern the lamp type of this backlight; With
(c) adjust the frequency of this alternating voltage according to this lamp type.
8. control method as claimed in claim 7 is characterized in that: this backlight control circuit further comprises a negative circuit, and in this step (a), this negative circuit drives this backlight with a direct current voltage transitions for this alternating voltage according to a pulse signal.
9. control method as claimed in claim 8, it is characterized in that: this backlight control circuit further comprises a pulse-width modulation integrated circuit, and this control method further comprises a step (d): this pulse-width modulation integrated circuit is exported this pulse signal to this negative circuit.
10. control method as claimed in claim 9, it is characterized in that: this backlight control circuit further comprises a fluorescent tube identification circuit and a frequency regulating circuit, this frequency regulating circuit comprises electric capacity, one variable resistor, one look-up table and a code translator, this pulse-width modulation integrated circuit comprises a power end and a frequency setting end, this power end connects this frequency setting end via this variable resistor, this frequency setting end is via this capacity earth, in this step (b), this fluorescent tube identification circuit is discerned the lamp type of this backlight according to the voltage and current in a period of time after this backlight startup; In this step (c) with (d), this look-up table arrives this code translator according to the instruction of lamp type output the type fluorescent tube correspondence of this fluorescent tube identification circuit identification, this code translator decipher should instruction be adjusted this variable-resistance conducting resistance, thereby the frequency of the pulse signal of this pulse-width modulation integrated circuit adjustment output, this negative circuit adjustment drives the frequency of the alternating voltage of this backlight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007100748099A CN101315486B (en) | 2007-06-01 | 2007-06-01 | Backlight control circuit and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007100748099A CN101315486B (en) | 2007-06-01 | 2007-06-01 | Backlight control circuit and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101315486A CN101315486A (en) | 2008-12-03 |
| CN101315486B true CN101315486B (en) | 2010-04-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007100748099A Expired - Fee Related CN101315486B (en) | 2007-06-01 | 2007-06-01 | Backlight control circuit and control method thereof |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101354359B1 (en) | 2009-12-22 | 2014-01-22 | 엘지디스플레이 주식회사 | Display Device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1387394A (en) * | 2001-05-22 | 2002-12-25 | 国碁电子股份有限公司 | Drive system of fluorescent lamp and fluorescent lamp system using it |
| US20030178951A1 (en) * | 2002-03-20 | 2003-09-25 | Park Jung Kook | Low noise backlight system for use in display device and method for driving the same |
| CN1691507A (en) * | 2004-04-19 | 2005-11-02 | 三洋电机株式会社 | Driver circuit |
| CN1856200A (en) * | 2005-04-29 | 2006-11-01 | 明基电通股份有限公司 | Lamp lighter with switchable working frequency |
-
2007
- 2007-06-01 CN CN2007100748099A patent/CN101315486B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1387394A (en) * | 2001-05-22 | 2002-12-25 | 国碁电子股份有限公司 | Drive system of fluorescent lamp and fluorescent lamp system using it |
| US20030178951A1 (en) * | 2002-03-20 | 2003-09-25 | Park Jung Kook | Low noise backlight system for use in display device and method for driving the same |
| CN1691507A (en) * | 2004-04-19 | 2005-11-02 | 三洋电机株式会社 | Driver circuit |
| CN1856200A (en) * | 2005-04-29 | 2006-11-01 | 明基电通股份有限公司 | Lamp lighter with switchable working frequency |
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| Publication number | Publication date |
|---|---|
| CN101315486A (en) | 2008-12-03 |
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Granted publication date: 20100421 Termination date: 20180601 |