CN105206230B - LCD backlight control circuit and its terminal device - Google Patents
LCD backlight control circuit and its terminal device Download PDFInfo
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- CN105206230B CN105206230B CN201510648994.2A CN201510648994A CN105206230B CN 105206230 B CN105206230 B CN 105206230B CN 201510648994 A CN201510648994 A CN 201510648994A CN 105206230 B CN105206230 B CN 105206230B
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Abstract
The invention discloses a kind of LCD backlight control circuit and its terminal devices.The LCD backlight control circuit includes：Light source, backlight drive circuit and discharge circuit.Wherein, discharge circuit includes PMOS switch；When the grid voltage of PMOS switch is less than its source voltage, discharge circuit source electrode is connected with drain electrode, is discharged over the ground；When the grid voltage of discharge circuit is equal to its source voltage, discharge circuit source electrode is disconnected with drain electrode.The present invention passes through above-mentioned LCD backlight control circuit, in powered-off fault, which can come out the residual charge quick release in circuit, the rapid backlight for closing LCD, the appearance of bad display situation such as the accumulation of residual charge is avoided, and then avoids grayscale ghost；The circuit has protection circuit function, avoids liquid crystal molecule from failing because of hyperpolarization, extends the service life of display device.
Description
Technical field
The present invention relates to LCD (Liquid Crystal Display) technical field of liquid crystal display, especially a kind of liquid crystal
Display backlight control circuit and its terminal device.
Background technology
Currently, LCD LCD technologies be widely used in large-sized television set, monitor and small-medium size tablet,
In the electronic products such as mobile phone.LCD is：Liquid crystal layer, liquid crystal drive electricity
Road, back light and backlight drive circuit etc., operation principle is developed the color using the optical activity of liquid crystal molecule, due to liquid crystal point
Son is being powered different with arrangement mode when no power, thus backlight is by the number of liquid crystal layer difference, finally allows LCD screen
Show different grayscale.
LCD on the market is typically to be driven with alternating current at present, to prevent liquid crystal molecule from losing because polarizing excessively
Lose turn-over capacity.When showing the power supply normal power down of equipment, the power supply of backlight LED light sources can be disconnected first, to ensure liquid crystal point
Son returns to state when blank screen.But after the power supply of display equipment unexpected abnormal power-down, all power supplys are nearly all disconnected simultaneously
Electricity, since the current potential in the input circuit of backlight LED light source is higher than backlight drive current potential, and its decrease speed is slower, from
And when backlight drive power supply being caused to have been switched off, the voltage in the input circuit of backlight LED light source is still in open state, therefore
Just cause backlight that can not completely close, consequence is to produce display ghost.
The case where for above-mentioned abnormal power-down, residual charge is released if do not adopted an effective measure, Bian Huiyou
Charge residue just will produce following several ask when remaining charge accumulation is to certain degree in liquid crystal layer and driving circuit
Topic：1. discharging between circuit, circuit is burnt out；2. form stable built-in DC electric field, make liquid crystal maintain deflection state and nothing
Method is restored, and eventually maintains to show a certain grayscale, forms ghost；Simultaneously DC electric field and make liquid crystal molecule polarize and fail.This
Kind display is bad to show as grayscale ghost when powered-off fault shuts down, and booting next time can also influence the gray-scale figure newly shown when restarting
Picture makes display quality greatly decline.
Invention content
The purpose of the present invention is to provide a kind of LCD backlight control circuit and its terminal devices, can fall in exception
In the case of electricity, the rapid backlight for closing LCD is realized, the bad display such as avoid the accumulation of residual charge, and then avoid grayscale ghost
The appearance of situation.
The present invention provides a kind of LCD backlight control circuit and its terminal devices comprising：
Light source, backlight drive circuit and discharge circuit；
The wherein described backlight drive circuit includes the first output end, and the light source includes first input end, the electric discharge electricity
Road includes control terminal, the second input terminal and second output terminal；
First output end of the wherein described backlight drive circuit is separately connected first input end and the institute of the light source
The control terminal of discharge circuit is stated, the second input terminal of the discharge circuit connects the first input end of the light source, the electric discharge
The second output terminal of circuit is electric current release end；
Wherein, when the control terminal voltage of the discharge circuit is less than the voltage of second input terminal, the discharge circuit
The second input terminal and the second output terminal connect, the control terminal voltage of the discharge circuit is equal to second input terminal
When voltage, the second input terminal and the second output terminal of the discharge circuit disconnect.
The wherein LCD backlight control circuit, the discharge circuit includes PMOS switch, the PMOS switch
Grid be the control terminal, the source electrode of the PMOS switch is second input terminal, and the drain electrode of the PMOS switch is institute
Second output terminal is stated, and is grounded.
The wherein described LCD backlight control circuit, the of the first input end of the light source and the discharge circuit
It is connected with current-limiting resistance between two input terminals.
The present invention provides a kind of terminal devices comprising：
Light source, mainboard, discharge circuit and LCD panel, the mainboard include backlight drive circuit, and the light source is described
LCD panel provides backlight；
The backlight drive circuit includes the first output end, and the light source includes first input end, the discharge circuit packet
Include control terminal, the second input terminal and second output terminal；
First output end of the backlight drive circuit is separately connected the first input end of the light source and described puts
The control terminal of circuit, the second input terminal of the discharge circuit connect the first input end of the light source, the discharge circuit
Second output terminal be electric current release end；
Wherein, when the control terminal voltage of the discharge circuit is less than the voltage of second input terminal, the discharge circuit
The second input terminal and the second output terminal connect, the control terminal voltage of the discharge circuit is equal to second input terminal
When voltage, the second input terminal and the second output terminal of the discharge circuit disconnect.
The wherein terminal device, the discharge circuit includes PMOS switch, and the grid of the PMOS switches is described
The source electrode of control terminal, the PMOS switch is second input terminal, and the drain electrode of the PMOS switch is the second output terminal,
And it is grounded.
The wherein terminal device, between the first input end of the light source and the second input terminal of the discharge circuit
It is connected with current-limiting resistance.
The wherein terminal device, further comprises the flexible circuit board for connecting the LCD panel, the software circuit
Plate is equipped with electrode pads, the electrode pads be connected to the light source and the backlight drive circuit first output end it
Between, the second input terminal of the discharge circuit connects the electrode pads.
The beneficial effects of the invention are as follows：In the prior art, when there is the case where abnormal power-down, charge can remain in liquid crystal
In layer and circuit, it will discharge between circuit when the charge accumulation in circuit is to certain degree, burn out circuit, and be likely to form
Stable built-in DC electric field, makes liquid crystal maintain the state of deflection and can not restore, and eventually maintains to show a certain grayscale, shape
At ghost, display quality is made greatly to decline.A kind of LCD backlight control circuit of present invention proposition and its terminal device.Wherein
LCD backlight control circuit, including backlight drive circuit, light source and discharge circuit；From effect, first, different
Under normal power-down conditions, which can come out the residual charge quick release in circuit, and the rapid backlight for closing LCD avoids
The accumulation of residual charge, and then the appearance for the bad display situation such as avoid grayscale ghost；Secondly, the circuit structure is simple, used
Element is cheap；Finally, which has protection circuit function, reduces the risk that liquid crystal molecule fails by hyperpolarization, prolongs
The service life of long display device.
Description of the drawings
Fig. 1 is the structural schematic diagram of LCD backlight control circuit first embodiment of the present invention；
Fig. 2 is the structural schematic diagram of discharge circuit in LCD backlight control circuit second embodiment of the present invention；
Fig. 3 is the structural schematic diagram of concatenated resistance in second embodiment in LCD backlight control circuit of the present invention；
Fig. 4 is the structural schematic diagram of the first embodiment of terminal device of the present invention；
Fig. 5 be terminal device of the present invention second embodiment in flexible circuit structural schematic diagram.
Specific implementation mode
As shown in Figure 1, the first embodiment of LCD backlight control circuit of the present invention includes：
Light source 11, backlight drive circuit 12 and discharge circuit 13；
Wherein backlight drive circuit 12 includes the first output end 121, and light source 1 includes first input end 111, discharge circuit
13 include control terminal 131, the second input terminal 132 and second output terminal 133；
First output end 121 of backlight drive circuit 12 is separately connected the first input end 111 and discharge circuit of light source 11
13 control terminal 131, the first input end 111 of the second input terminal 132 connection light source 11 of discharge circuit 13, discharge circuit 13
Second output terminal 133 is electric current release end；
In the circuit, control of the output voltage of 12 first output end 121 of backlight drive circuit as discharge circuit 13
Voltage controls the connection and disconnection of the second input terminal 132 and second output terminal 133 of discharge circuit 13.Specifically it is divided into two kinds
Working condition is described：
When the circuit is in normal operating conditions, the output voltage of 12 first output end 121 of backlight drive circuit is equal to
The voltage of the first input end 111 of light source 11, at this point, the second input terminal 132 of discharge circuit 13 and second output terminal 133 are disconnected
It opens, the first output end 121 of backlight drive circuit 12 is connected to light source 11, provides driving voltage for light source 11, this voltage swing
Size depending on liquid crystal display panel and required display brightness.
When the circuit is in abnormal operation, such as when 12 abnormal electrical power supply of abnormal power-down or backlight drive circuit, this
When backlight drive circuit 12 and light source 11 current potential it is high and the velocity of discharge is slow, thus have charge residue in circuit；In this shape
Under state, the output voltage of 12 first output end 121 of backlight drive circuit is less than the voltage of the first input end 111 of light source 11, puts
Second input terminal 132 of circuit 13 is connected to second output terminal 133, the charge in power supply 11 pass through discharge circuit 13
Two output ends 132 are discharged into other than circuit.
As shown in Fig. 2, the second embodiment of LCD backlight control circuit of the present invention is substantially similar to first embodiment,
Main difference is that discharge circuit therein includes：PMOS switch 21.
As shown in Fig. 2, PMOS switch includes three electrodes：Grid G, source S and drain D, wherein grid G are discharge circuits
23 control terminal, source S are the second input terminals of discharge circuit 23, and drain D is the second output terminal of discharge circuit 23, and connects
Ground.In the circuit, PMOS switches 24 are used as monitoring objective current potential by the current potential of grid G, when the current potential of grid G is equal to light
When the current potential of the first input end 211 in source 21, PMOS switch 24 disconnects, the first output end and light source of backlight drive circuit 22
21 connections provide driving voltage for light source 21；When the current potential of grid G is less than 211 current potential of first input end of light source 21,
PMOS switch 24 is connected to, and the charge in power supply 21 is discharged by the drain D of PMOS switch 24 other than circuit.
The 3rd embodiment of LCD backlight control circuit of the present invention is on the basis of second embodiment, about electricity
The structural representation of concatenated resistance in road；
As shown in figure 3, a current-limiting resistance 35 of connecting between the source S and light source 31 of PMOS switch 34, resistance is big
Small is 1K Ω or so, and resistance is smaller, and discharge current is bigger, and electric discharge is faster.Current-limiting resistance 35 plays stabilization in this circuit arrangement
The effect of voltage, protective resistance, principle be, using Ohm's law come the size of current in limiting circuit, allows electricity in circuit
Stream is unlikely to excessive, prevents electric current excessive to damage caused by current loading end PMOS switch 34.
In working condition, when the current potential of the grid G of PMOS switch 34 is less than the current potential of the first input end 311 of light source 31
When, PMOS switch 34 is connected to, the charge in power supply 1 by the drain D of current-limiting resistance 35 and PMOS switch 34 be discharged into circuit with
Outside.The size of current-limiting resistance 35 depends on supply voltage, operating voltage etc., so to select corresponding model in different circuits
Current-limiting resistance 35 and PMOS switch 34.
The first embodiment of terminal device of the present invention, as shown in Figure 4 comprising：Light source 41, mainboard 42, discharge circuit 43
And LCD panel 44；Wherein mainboard 42 includes backlight drive circuit 45, and wherein light source 41 is that the LCD panel 44 provides backlight；
Wherein backlight drive circuit 45 includes the first output end 451, and light source 41 includes first input end 411, discharge circuit
43 include control terminal 431, the second input terminal 432 and second output terminal 433；
First output end 451 of backlight drive circuit 45 is separately connected the first input end 411 and discharge circuit of light source 41
43 control terminal 431, the first input end 411 of the second input terminal 432 connection light source 41 of discharge circuit 43, discharge circuit 43
Second output terminal 433 is electric current release end；
In the terminal device, the output voltage of 45 first output end 451 of backlight drive circuit is as discharge circuit 43
Voltage is controlled, the connection and disconnection of the second input terminal 432 and second output terminal 433 of discharge circuit 43 are controlled.Specifically it is divided into
Two kinds of working conditions are described：
When the terminal device is in normal operating conditions, 45 first output end 451 of backlight drive circuit on mainboard 42
Output voltage be equal to light source 41 first input end 411 voltage, at this point, the second input terminal 432 of discharge circuit 43 and the
Two output ends 433 disconnect, and the first output end 451 of the backlight drive circuit 45 on mainboard 42 is connected to light source 41, are light source 41
There is provided driving voltage makes light source 41 shine, and then light source 41 is that LCD panel 44 provides backlight, so that the terminal device is realized normal
Display function.The driving voltage size that backlight drive circuit 45 wherein on mainboard 42 provides depend on liquid crystal display panel size and
Required display brightness.
When the terminal device is in abnormal operation, such as 45 abnormal electrical power supply of abnormal power-down or backlight drive circuit
When, the output voltage of electric 45 first output ends 451 of backlight drive is less than the voltage of the first input end 411 of light source 41 at this time, this
When, the second input terminal 432 of discharge circuit 43 is connected to second output terminal 433, and the charge in power supply 41 passes through discharge circuit 43
Second output terminal 433 be discharged into other than the equipment.
As shown in figure 5, the second embodiment of terminal device of the present invention is substantially similar to first embodiment, main difference
It is that the terminal device further includes a flexible circuit board for being connected to LCD panel 54 55, flexible circuit board 55 is the driving of LCD
Circuit, flexible circuit board 55 are equipped with electrode pads 56, and electrode pads are connected between light source 51 and backlight drive circuit 52, and
The 532 connection electrode gasket 56 of the second input terminal of discharge circuit 53.
LCD backlight control circuit of the present invention is not only applicable in LCD panel, also may be used in OLED display panel modules
With application.
LCD backlight control circuit of the present invention has good benefit in practical applications.First, in powered-off fault
In the case of, which can come out the residual charge quick release in circuit, and the rapid backlight for closing LCD avoids residual electricity
The accumulation of lotus, and then the appearance for the bad display situation such as avoid grayscale ghost；Secondly, the circuit structure is simple, and element used is honest and clean
Valence will not increase cost；Finally, which has protection circuit function, and liquid crystal molecule is avoided to fail because of hyperpolarization, extends
The service life of display device.
Mode the above is only the implementation of the present invention is not intended to limit the scope of the invention, every to utilize this
Equivalent structure or equivalent flow shift made by description of the invention and accompanying drawing content, it is relevant to be applied directly or indirectly in other
Technical field is included within the scope of the present invention.
Claims (7)
1. a kind of LCD backlight control circuit, which is characterized in that including：
Light source, backlight drive circuit and discharge circuit；
The backlight drive circuit includes the first output end, and the light source includes first input end, and the discharge circuit includes control
End, the second input terminal and second output terminal processed；
First output end of the backlight drive circuit is separately connected the first input end and electric discharge electricity of the light source
The control terminal on road, the second input terminal of the discharge circuit connect the first input end of the light source, and the of the discharge circuit
Two output ends are electric current release ends；
Wherein, when the control terminal voltage of the discharge circuit is less than the voltage of second input terminal, the of the discharge circuit
Two input terminals are connected with the second output terminal, and the control terminal voltage of the discharge circuit is equal to the voltage of second input terminal
When, the second input terminal and the second output terminal of the discharge circuit disconnect.
2. LCD backlight control circuit according to claim 1, which is characterized in that
The discharge circuit includes PMOS switch, and the grid of the PMOS switch is the control terminal, the source of the PMOS switch
Pole is second input terminal, and the drain electrode of the PMOS switch is the second output terminal, and is grounded.
3. LCD backlight control circuit according to claim 2, which is characterized in that
It is connected with current-limiting resistance between the first input end of the light source and the second input terminal of the discharge circuit.
4. a kind of terminal device, which is characterized in that including：
Light source, mainboard, discharge circuit and LCD panel, the mainboard include backlight drive circuit, and the light source is the LCD
Panel provides backlight；
The backlight drive circuit includes the first output end, and the light source includes first input end, and the discharge circuit includes control
End, the second input terminal and second output terminal processed；
First output end of the backlight drive circuit is separately connected the first input end and electric discharge electricity of the light source
The control terminal on road, the second input terminal of the discharge circuit connect the first input end of the light source, and the of the discharge circuit
Two output ends are electric current release ends；
Wherein, when the control terminal voltage of the discharge circuit is less than the voltage of second input terminal, the of the discharge circuit
Two input terminals are connected with the second output terminal, and the control terminal voltage of the discharge circuit is equal to the voltage of second input terminal
When, the second input terminal and the second output terminal of the discharge circuit disconnect.
5. terminal device according to claim 4, which is characterized in that
The discharge circuit includes PMOS switch, and the grid of the PMOS switch is the control terminal, the source of the PMOS switch
Pole is second input terminal, and the drain electrode of the PMOS switch is the second output terminal, and is grounded.
6. terminal device according to claim 5, which is characterized in that
It is connected with current-limiting resistance between the first input end of the light source and the second input terminal of the discharge circuit.
7. according to claim 4 to 6 any one of them terminal device, which is characterized in that
Further comprise that the flexible circuit board for connecting the LCD panel, the flexible circuit board are equipped with electrode pads, the electrode
Gasket is connected between the light source and first output end of the backlight drive circuit, and the second of the discharge circuit is defeated
Enter end and connects the electrode pads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510648994.2A CN105206230B (en) | 2015-10-09 | 2015-10-09 | LCD backlight control circuit and its terminal device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510648994.2A CN105206230B (en) | 2015-10-09 | 2015-10-09 | LCD backlight control circuit and its terminal device |
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| Publication Number | Publication Date |
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| CN105206230A CN105206230A (en) | 2015-12-30 |
| CN105206230B true CN105206230B (en) | 2018-07-17 |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10834795B2 (en) | 2018-05-16 | 2020-11-10 | Hisense Visual Technology Co., Ltd. | Backlight drive circuit, backlight driving method, and display device |
| CN112086074A (en) * | 2018-05-16 | 2020-12-15 | 海信视像科技股份有限公司 | Multi-partition backlight driving circuit and display device |
| WO2019218568A1 (en) * | 2018-05-16 | 2019-11-21 | 青岛海信电器股份有限公司 | Backlight driving circuit, backlight driving method, and display device |
| CN109509451B (en) * | 2018-12-21 | 2021-04-27 | 惠科股份有限公司 | Display device |
| CN114999323B (en) * | 2022-06-15 | 2023-11-07 | 深圳英众世纪智能科技有限公司 | Backlight driving circuit and terminal equipment |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100583223C (en) * | 2006-10-27 | 2010-01-20 | 上海广电Nec液晶显示器有限公司 | Control device for quick clearing liquid crystal display panel ghost |
| TWI402805B (en) * | 2010-04-20 | 2013-07-21 | Chunghwa Picture Tubes Ltd | Voltage converter and driving method for use in a backlight module |
| US8237640B2 (en) * | 2010-05-24 | 2012-08-07 | Immense Advance Technology Corp. | LED driver circuit having a bias current drawn from a load current |
| CN102842292A (en) * | 2011-06-24 | 2012-12-26 | 鸿富锦精密工业（深圳）有限公司 | Power supply management circuit and display device using same |
| CN102522063A (en) * | 2011-12-05 | 2012-06-27 | 杭州士兰控股有限公司 | LED (light-emitted diode) display system capable of eliminating dynamic LED display ghost |
| CN103927993B (en) * | 2013-12-18 | 2016-04-27 | 上海中航光电子有限公司 | Display backlight control circuit, method and display device |
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