KR20090047298A - Inverter driving circuit for liquid crystal display device - Google Patents

Inverter driving circuit for liquid crystal display device Download PDF

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Publication number
KR20090047298A
KR20090047298A KR1020070113389A KR20070113389A KR20090047298A KR 20090047298 A KR20090047298 A KR 20090047298A KR 1020070113389 A KR1020070113389 A KR 1020070113389A KR 20070113389 A KR20070113389 A KR 20070113389A KR 20090047298 A KR20090047298 A KR 20090047298A
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KR
South Korea
Prior art keywords
inverter
resistance value
unit
lamp
resistor
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KR1020070113389A
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Korean (ko)
Inventor
김승현
이대흥
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엘지디스플레이 주식회사
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Priority to KR1020070113389A priority Critical patent/KR20090047298A/en
Publication of KR20090047298A publication Critical patent/KR20090047298A/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
    • H05B41/2821—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage
    • H05B41/2822—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0252—Improving the response speed
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/041—Temperature compensation

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

The present invention relates to a technique for preventing a phenomenon in which the temperature around the fluorescent lamp on the backlight unit is lowered at low temperature in the liquid crystal display device. As described above, the present invention includes installing a dummyster on the lamp support of the backlight unit, and using the same, detecting a temperature change around the initial lamp of the inverter and the backlight lamp thereafter, and outputting a resistance value adjustment signal accordingly. Wealth; A resistance value setting unit for setting a high resistance value at an initial driving time of the inverter according to the resistance value adjustment signal and thereafter setting the resistance value to its original value; A control unit which outputs a driving control signal to an inverter output unit based on the resistance value set by the resistance setting unit; According to the drive control signal, the inverter initially outputs a higher power by lowering the driving frequency of the lamp on the backlight unit, and then returns to the original driving frequency to supply the power of the originally set level. It is characterized by the configuration of wealth. Accordingly, it is possible to quickly and accurately detect the temperature change around the backlight lamp, thereby rapidly increasing the driving voltage of the fluorescent lamp, thereby solving the partial lighting problem and obtaining a quick response characteristic.

Backlight Unit, Fluorescent Lamp, Low Temperature Lighting

Description

 Inverter driving circuit of liquid crystal display device {INVERTER DRIVING CIRCUIT FOR LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling the lighting of a backlight in a liquid crystal display device. In particular, an inverter driving circuit of a liquid crystal display device suitable for preventing the occurrence of low-temperature lighting of a lamp by detecting a temperature around the lamp at the initial stage of backlight driving. It's about the furnace.

In general, liquid crystal display (LCD) is in the situation that its application range is gradually expanded due to the characteristics such as light weight, thinness, low power consumption. According to this trend, LCDs are widely used in office automation equipment, audio / video equipment, and the like. The LCD displays a desired image on the screen by adjusting the transmission amount of the light beam according to an image signal applied to the control switches arranged in a matrix form.

However, the LCD is not a display device that emits light by itself, and thus requires a light source such as a backlight unit. An example of a light source used as the backlight unit may be a Cold Cathode Fluorescent Tube (CCFL). The backlight lamp is a light source tube using a cold cathode emission phenomenon, and low heat generation, high brightness, long life, full color is easy. The liquid crystal display using such a lamp uses a direct type backlight unit using a plurality of lamps according to the trend of larger size.

The direct type backlight unit has a problem in that only some of them are driven by discharge characteristics when driving multiple CCFLs in parallel using a single transformer. In order to solve this problem, by attaching the same capacitor (Ballast Capacitor) to the positive electrodes of a plurality of CCFLs to form the same equivalent circuit as the External Electrode Fluorescent (EEFL) by using a plurality of CCFLs A lamp driving device of a liquid crystal display device capable of parallel driving of them has been proposed.

Here, the external electrode fluorescent lamp is turned on by applying an AC waveform to the external electrode. That is, the external electrode fluorescent lamp is discharged in the discharge space inside the glass tube by a high frequency electric field applied to a pair of external electrodes, and the phosphor coated on the inner wall of the glass tube by the ultraviolet rays generated by the discharge emits light. And visible light is generated.

In general, an inverter is used to turn on the fluorescent lamp, and the temperature of the inverter is low during initial driving. For this reason, the voltage or tube current supplied to the fluorescent lamp through the transformer was below the reference value.

As described above, in the inverter of the conventional liquid crystal display, the temperature of the inverter often drops below the reference value during the initial driving of the fluorescent lamp. For this reason, the fluorescent lamp is not turned on with uniform brightness, and abnormal lighting such as partial lighting occurs. Accordingly, there has been a difficulty in providing high quality images.

Recently, a technique for solving the partial lighting problem by increasing the driving voltage of the lamp during initial driving by detecting the temperature around the inverter has been proposed, but it is not possible to quickly detect and reflect the ambient temperature around the fluorescent lamp, resulting in a quick response. There was a problem that the characteristics could not be obtained. Moreover, this phenomenon is more severe in large panels, which is one factor that lowers the confidence in the product.

Accordingly, an object of the present invention is to check the temperature of the inverter in the initial stage of driving the fluorescent lamp on the backlight unit quickly and accurately to prevent the low temperature lighting phenomenon of the lamp by adjusting the lamp driving current or the driving voltage when it is below the reference value.

The present invention for achieving the above object, by installing a dummy sensor which is a temperature sensor on the lamp support installed on the back of the lower cover of the backlight unit, by using the temperature, the initial temperature of the inverter and the temperature around the fluorescent lamp thereafter A temperature sensor for detecting a change and outputting a resistance value adjustment signal accordingly; A resistance value setting unit for setting different initial and late resistance values of the inverter according to the resistance value adjustment signal; A control unit which outputs a driving control signal to an inverter output unit based on the resistance value set by the resistance setting unit; According to the control signal output from the control unit in the initial stage of driving the inverter output unit for increasing the output level of the fluorescent lamp on the backlight unit, after that it is characterized in that it comprises a inverter output unit for returning to the original output level level.

According to the present invention, when the temperature of the inverter is checked at an initial stage of lamp driving, the lamp driving current or the driving voltage is adjusted so that the low temperature of the lamp does not occur by adjusting the lamp driving current or the driving voltage, thereby giving the user confidence in the product. .

In addition, by installing a dummy sensor as a temperature sensor in one of the lamp holders on the lamp support to detect the ambient temperature of the fluorescent lamp, the ambient temperature can be detected quickly and accurately, thereby driving the fluorescent lamp. By increasing the voltage quickly, the problem of partial lighting is solved and the fast response characteristic can be obtained.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1A schematically shows an inverter to which the present invention is applied. As shown in FIG. 1A, a main inverter 10A and a slave inverter 10B are respectively mounted on a lower cover 10 of a backlight unit, and any one of them is mounted. The inverter control circuit is configured to be mounted.

1b shows an installation portion of a dummy sensor which is a temperature sensor according to the present invention. As shown in FIG. 1, a lamp support 11 is installed on a rear surface of the lower cover 10, and lamp holders are provided at regular intervals. 12) is installed, a dummyster (TH) for temperature sensing is installed in one of the lamp holder (12).

FIG. 2 is a block diagram showing an embodiment of a frequency variable type in an inverter driving circuit of a liquid crystal display according to the present invention. As shown in FIG. 2, the additional device is provided between lamp holders 12 on the lamp support 11. A temperature sensing unit 21 for detecting a temperature change around the fluorescent lamp for the backlight using the MR TH and outputting a resistance value adjustment signal accordingly; A resistance value setting unit 22 for setting a high resistance value at an initial driving time of the inverter according to the resistance value adjustment signal and thereafter setting the resistance value to its original value; A controller 23 for outputting a driving control signal to the inverter output unit 24 based on the resistance value set by the resistance value setting unit 22; According to the control signal output from the controller 23, the drive frequency of the inverter is initially lowered so that higher power is supplied to the lamp on the backlight unit, and afterwards, the original power is supplied by returning to the original drive frequency. Inverter output section 24 to be configured.

3 is a circuit diagram showing an embodiment of the temperature sensing unit 21 and the resistance setting unit 22. As shown therein, a power supply terminal VCC is provided to detect a temperature change around a fluorescent lamp for a backlight. A dummy connection (TH) and a resistor (R31) connected in series between a ground terminal and a ground terminal and mounted on a lamp support; A comparator (CP31) for comparing the temperature sensing voltage (Vsns) output from the connection point of the dummy (TH) and the resistor (R31) with a reference voltage (Vref) and outputs a signal according thereto; In accordance with the output signal of the comparator (CP31) one transistor (R33) is connected between the resistance terminal (RT) and the ground terminal, or the transistor (R33) and the other resistor (R34) to be connected in parallel M31), the operation of the present invention configured as described in detail as follows.

Figure 1a shows a schematic block diagram of an inverter to which the present invention is applied. That is, the main inverter 10A and the slave inverter 10B are respectively mounted on the lower cover 10 of the backlight unit, and any one of them is mounted with an inverter control circuit as shown in FIG. 2 or 4 to be described later.

Figure 1b shows the installation site of the dummy sensor which is a temperature sensor according to the present invention. That is, the lamp support 11 is installed on the rear surface of the lower cover 10 in which the main inverter 10A and the slave inverter 10B are installed, and lamp holders 12 are installed at predetermined intervals, thereby providing respective fluorescent lamps ( 13) are mounted, and light emitted from them is irradiated to the liquid crystal panel side.

In the present invention, a dummy sensor (TH), which is a temperature sensor, is installed at one of the lamp holders 12 on the lamp support 11, and when the external electrode fluorescent lamp (EEFL) is used as the fluorescent lamp 13, The electrode of the extra-electrode fluorescent lamp EEFL is fixed to the lamp support 11. Since the electrode of the external electrode fluorescent lamp (EEFL) is made of metal, it reacts sensitively to changes in ambient temperature. The dummyster TH was installed at the electrode portion.

Therefore, the atmosphere temperature of the fluorescent lamp 13 can be detected most quickly and accurately at the beginning of driving, and the driving voltage thereof is quickly raised to solve the problem of partial lighting and to obtain a fast response characteristic.

Referring to FIG. 3, the operation of the temperature sensing unit 21 and the resistance value setting unit 22 will be described with reference to FIG. 2.

The power supply terminal VCC is connected to the ground terminal through the dummyster TH and the resistor R31 connected in series, and the connection point between the dummyster TH and the resistor R31 is the non-inverting input terminal of the comparator CP31. The inverting input terminal of the comparator CP31 is supplied with a reference voltage Vref.

In general, since the components are not heated in the initial stage of driving in which the fluorescent lamps 13 are turned on by the main inverter 10A and the slave inverter 10B in the liquid crystal display, the temperature around the fluorescent lamp 13 is reduced. Is low. Therefore, at this time, the resistance value of the dummy (TH) is relatively high. For reference, the dummy (TH) may be implemented as a negative characteristic dummyster or a positive characteristic dummyster, in this case, it is assumed that the dummyster TH.

Accordingly, the temperature sensing voltage Vsns output at the connection point between the dummyster TH and the resistor R31 is lower than after the liquid crystal display is driven to some extent. At this time, the reference voltage Vref is set such that the temperature sensing voltage Vsns is lower than the reference voltage Vref supplied to the non-inverting input terminal of the comparator CP31.

Therefore, since the 'low' is output from the comparator CP31, the MOS transistor M31 is thereby turned off. Therefore, the resistor R34 on the resistance value setting section 22 is in a floating state. As a result, the total resistance value on the resistance value setting section 22 is determined solely by one resistor R33, which is higher than the later stage of driving. To this end, in the present embodiment, the values of the two resistors R33 and R34 are set to the same or similar values.

After a predetermined time has elapsed, a large amount of heat is generated from the heat generating component, for example, the fluorescent lamp 13 on the backlight unit or a transformer provided on the main inverter 10A and the slave inverter 10B. For this reason, the resistance value of the dummyster TH is relatively low.

Accordingly, the temperature sensing voltage Vsns output at the connection point between the dummyster TH and the resistor R31 is increased compared to the initial driving time, and is higher than the reference voltage Vref.

Therefore, at this time, 'high' is output from the comparator CP31, whereby the MOS transistor M31 is turned on. Therefore, the resistor R33 on the resistance value setting section 22 is connected in parallel with the resistor R34. For this reason, the total resistance value on the resistance value setting section 22 is reduced by half compared to the initial time of driving.

The control unit (Main IC) 23 changes the total resistance value of the resistance value setting unit 22 based on the voltage change of the resistance connection terminal RT of the resistance value setting unit 22 as described above. It recognizes and outputs the lamp driving frequency control signal according to the inverter output unit 24. Accordingly, the lamp driving frequency of the inverter output unit 24 is changed, thereby changing the brightness of the lamp on the backlight unit.

For example, in the initial state in which the backlight unit starts to be driven, the resistance value of the resistance setting unit 22 becomes relatively high through the above process, and the control unit 23 of the resistance connection terminal RT After recognizing that the resistance value is changed based on the voltage change, the lamp driving frequency control signal is output to the inverter output unit 24. As a result, the lamp driving frequency output from the inverter output unit 24 is lowered.

Therefore, the driving power (current or voltage) supplied from the inverter output unit 24 to the fluorescent lamp 13 is increased by that much, so that low-temperature lighting does not occur.

After a certain amount of time has elapsed, the total resistance value of the resistance setting unit 22 is set to be relatively low through the above-described process, and the control unit 23 performs the total resistance value in the same manner as described above. After recognizing the change, the inverter output unit 24 is controlled to output the lamp driving frequency output from the original level.

Accordingly, the driving power supplied from the inverter output unit 24 to the fluorescent lamp 13 is output as it is, but at this time, since the fluorescent lamp 13 is sufficiently warmed up, the low temperature lighting phenomenon does not occur. Do not.

In the main inverter 10A, the control unit 23 controls the output of the inverter output unit 24 as described above, and the slave inverter 10B in order to control the output in the same manner in the slave inverter 10B. Output control signal (CTL) is output to 10B).

On the other hand, Figure 4 is a block diagram showing an embodiment of the current variable in the inverter drive circuit of the liquid crystal display according to the present invention, as shown therein, the dummyster (installed on the lamp support 11 of the backlight unit ( A temperature sensing unit 41 which detects the initial temperature of the driving around the backlight fluorescent lamp and the temperature change thereafter using TH) and outputs a resistance value adjustment signal according thereto; A feedback resistor unit 42 which sets a low resistance value at an initial driving time of the inverter according to the resistance value adjustment signal and thereafter sets the resistance value to a high value as originally; A control unit 43 for outputting an output current control signal to the inverter output unit 44 based on the resistance value set by the feedback resistor unit 42; According to the output current control signal output from the control unit 43, the initial stage of the driving was increased by the amount of tube current for the fluorescent lamp 13 on the backlight unit, and then composed of the inverter output unit 44 that outputs as it is.

FIG. 5 is a circuit diagram illustrating an exemplary embodiment of the temperature sensing unit 41 and the feedback resistor unit 42. As shown in FIG. The dummy stator (TH) and a resistor (R51) connected in series between a VCC) and a ground terminal; A comparator (CP51) for comparing the temperature sensing voltage (Vsns) output from the connection point of the dummy (TH) and the resistor (R51) with a reference voltage (Vref) and outputs a signal according thereto; According to the output signal of the comparator CP51, only the resistors R53, R54, R55, R56, and R57, R58 connected in parallel after being connected in series between the transformer output terminal OUT_TRANS and the ground terminal, or A transistor M51 for connecting these and other resistors R52 in parallel; Diodes D51 and D52 outputting a temperature sensing current Isns corresponding to the connection state of the resistors R52, R53, R54, R55, R56, and R57, R58. The operation of the present invention configured as described above will be described in detail as follows.

The operation of the temperature sensing unit 41 and the feedback resistor unit 42 in FIG. 4 will be described with reference to FIG. 5.

The power supply terminal VCC is connected to the ground terminal through the dummyster TH and the resistor R51 connected in series, and the connection point of the dummyster TH and the resistor R51 is connected to the inverting input terminal of the comparator CP51. The reference voltage Vref is supplied to the vision input terminal of the comparator CP51.

In general, since the components are not heated in the initial stage when the fluorescent lamps 13 on the backlight unit are turned on by the main inverter 10A and the slave inverter 10B in the liquid crystal display device, the periphery of the fluorescent lamp 13 is reduced. The temperature of is low. Therefore, at this time, the resistance value of the dummyster TH installed between the lamp holders 12 on the lamp support 11 of the backlight unit becomes relatively high. For reference, the dummy (TH) may be implemented as a negative characteristic dummyster or a positive characteristic dummyster, in this case, it is assumed that the dummyster TH.

Accordingly, the temperature sensing voltage Vsns output at the initial stage of driving at the connection point between the dummy TH and the resistor R51 is lower than after the liquid crystal display is driven to some extent. In this case, the reference voltage Vref is set such that the temperature sensing voltage Vsns is lower than the reference voltage Vref supplied to the inverting input terminal of the comparator CP51.

Therefore, since the high is output from the comparator CP51, the MOS transistor M51 is turned on by this. Therefore, the resistors R53, R54, (R55, R56), (R57, R58) in which the resistor R52 is connected in parallel after the series connection is made between the transformer output terminal OUT_TRANS and the ground terminal in the feedback resistor unit 42. Are connected in parallel.

As a result, the total resistance value on the feedback resistor portion 42 is relatively low. However, it is assumed that the values of the resistors R52-R58 are the same.

For this reason, the value of the temperature sensing current Isns output at this time is higher than in the late drive.

However, after the backlight unit is driven for a predetermined time or more, relatively much heat is generated thereby. Accordingly, the resistance value of the installed dummyster TH falls below a predetermined value.

Therefore, the temperature sensing voltage Vsns output at the connection point between the dummyster TH and the resistor R51 is higher than in the initial driving. At this time, the temperature sensing voltage Vsns is higher than the reference voltage Vref supplied to the non-inverting input terminal of the comparator CP51.

Accordingly, since the 'low' is output from the comparator CP51, the MOS transistor M51 is turned off by this. Therefore, in the feedback resistor section 42, the resistor R52 is in a floating state from the transformer output terminal OUT_TRANS. As a result, only the resistors R53, R54, R55, R56, and R57, R58 connected in parallel after the series connection between the transformer output terminal OUT_TRANS and the ground terminal are connected in parallel.

Therefore, at this time, when the total resistance value on the feedback resistor section 42 is connected in parallel with the resistors R53, 54, (R55, R56), and (R57, R58) connected in series with the resistor R2, respectively. It is higher than that.

Therefore, the value of the temperature sensing current Isns output at this time is lower than the value output at the initial stage of driving.

The control unit (Main IC) 43 recognizes the temperature change around the fluorescent lamp 13 based on the temperature sensing current Isns of the feedback resistor 42 output as described above, and outputs it from the inverter output unit 44. The tube current of the fluorescent lamp 13 is changed, whereby the brightness of the fluorescent lamp 13 on the backlight unit is changed.

For example, in the initial state in which the backlight unit starts to be driven, the value of the temperature sensing current Isns becomes higher as compared with the later stage of driving, as described in the above description. Based on the value of Isns), the output current control signal is output so that the tube current amount of the fluorescent lamp 13 output from the inverter output section 44 is slightly increased.

Accordingly, the amount of tube current supplied from the inverter output unit 44 to the fluorescent lamp 13 is increased, whereby a low temperature lighting phenomenon of the fluorescent lamp 13 does not occur.

After a certain time has elapsed, the value of the temperature sensing current Isns is output at a lower value than the initial stage of driving as described above. At this time, the control unit 43 lowers the amount of tube current of the fluorescent lamp 13 output from the inverter output unit 44 based on the lowered temperature sensing current Isns and outputs an output current control signal so as to be output as it is. Output

Accordingly, the amount of tube current supplied from the inverter output unit 44 to the fluorescent lamp 13 is slightly reduced. At this time, since the fluorescent lamp 13 is sufficiently warmed up, the lamp is normally turned on so that low temperature does not occur. .

1A is a schematic block diagram of an inverter to which the present invention is applied.

Figure 1b is a schematic view showing the installation site of the dummy sensor temperature sensor according to the present invention.

2 is a block diagram of a frequency variable inverter of a liquid crystal display according to the present invention.

3 is a detailed circuit diagram of a temperature sensing unit and a resistance value setting unit of FIG. 2.

4 is a block diagram of a current variable inverter of a liquid crystal display according to the present invention.

FIG. 5 is a detailed circuit diagram of a temperature sensing unit and a feedback resistor unit in FIG. 4.

*** Description of the symbols for the main parts of the drawings ***

10: lower cover 10A: main inverter

10B: slave inverter 11: lamp support

12 lamp holder 13 fluorescent lamp

21: temperature sensing unit 22: resistance value setting unit

23 control unit 24 inverter output unit

Claims (7)

A temperature sensing unit which installs a dummyster on a lamp support of the backlight unit, detects a temperature change around the initial stage of the inverter and a subsequent backlight lamp by using the same, and outputs a resistance value adjustment signal accordingly; A resistance value setting unit for setting a high resistance value at an initial driving time of the inverter according to the resistance value adjustment signal and thereafter setting the resistance value to its original value; A control unit which outputs a driving control signal to an inverter output unit based on the resistance value set by the resistance setting unit; According to the drive control signal, the inverter initially outputs a higher power by lowering the driving frequency of the lamp on the backlight unit, and then returns to the original driving frequency to supply the power of the originally set level. Inverter drive circuit of a liquid crystal display device characterized in that the configuration. The method of claim 1, wherein the temperature sensing unit It is installed on the lamp support of the backlight unit and connected in series with the dummyster TH between the power supply terminal VCC and the ground terminal to detect the temperature change around the backlight lamp during the initial and subsequent driving of the inverter. Resistor R31; And a comparator (CP31) for comparing the connection point voltages of the dummyster (TH31) and the resistor (R31) with a reference voltage (Vref) and outputting a signal accordingly. 3. The inverter driving circuit of claim 2, wherein the dummyster is a negative characteristic dummyster. The resistor setting unit of claim 1, wherein the resistor setting unit causes one resistor R33 to be connected between the resistor connection terminal RT and the ground terminal according to the output signal of the comparator CP31, or the resistor R33 is different from the resistor R33. Inverter drive circuit of a liquid crystal display device comprising a transistor (M31) for allowing R34) to be connected in parallel. A temperature sensing unit which installs a dummyster on a lamp support of the backlight unit, detects a temperature change around the initial stage of the inverter and a subsequent backlight lamp by using the same, and outputs a resistance value adjustment signal accordingly; A feedback resistor unit which sets a low resistance value at an initial stage of the drive of the inverter according to the resistance value adjustment signal and thereafter sets the resistance value to its original value; A control unit which outputs an output current control signal to an inverter output unit based on the resistance value set by the feedback resistor unit; Inverter driving circuit of the liquid crystal display device, characterized in that the inverter output unit for increasing the tube current amount to the lamp on the backlight unit at the beginning of the drive in accordance with the output current control signal, and after that to return to the original tube current amount level . The method of claim 5, wherein the temperature sensing unit It is installed on the lamp support of the backlight unit, the dummyster TH for detecting the temperature change around the backlight lamp during the initial and subsequent driving of the inverter, and the dummyster TH between the power supply terminal VCC and the ground terminal. A resistor R51 connected in series with the resistor; And a comparator (CP51) for comparing the connection point voltages of the dummy (TH51) and the resistor (R51) with a reference voltage (Vref) and outputting a signal corresponding thereto. The method of claim 5, wherein the feedback resistor is According to the output signal of the comparator CP51, the resistors R53, R54, R55, R56, and R57, R58 connected in parallel after the series connection between the transformer output terminal OUT_TRANS and the ground terminal are connected, or A transistor M51 for allowing a different resistor R52 to be connected in parallel; And a diode (D51) and (D52) for outputting a DC voltage of a level corresponding to the connection state of the resistor (R52) and resistors (R53, R54), (R55, R56), (R57, R58). An inverter driving circuit of a liquid crystal display device.
KR1020070113389A 2007-11-07 2007-11-07 Inverter driving circuit for liquid crystal display device KR20090047298A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111145697A (en) * 2018-11-02 2020-05-12 茂达电子股份有限公司 Backlight device and dimming control method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111145697A (en) * 2018-11-02 2020-05-12 茂达电子股份有限公司 Backlight device and dimming control method thereof

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