CN201804537U - Current control module of LCD (liquid crystal display) backlight of mobile terminal - Google Patents
Current control module of LCD (liquid crystal display) backlight of mobile terminal Download PDFInfo
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- CN201804537U CN201804537U CN201020287318XU CN201020287318U CN201804537U CN 201804537 U CN201804537 U CN 201804537U CN 201020287318X U CN201020287318X U CN 201020287318XU CN 201020287318 U CN201020287318 U CN 201020287318U CN 201804537 U CN201804537 U CN 201804537U
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Abstract
The utility model discloses a current control module of an LCD backlight of a mobile terminal, wherein, the current control module is arranged between an LCD backlight drive IC (integrated circuit) and an LCD backlight LED lamp group, the current control module comprises a charge pump and an MOS (metal-oxide-semiconductor) transistor group, the input end of the charge pump is connected with a power supply, the output end of the charge pump is connected with the LED lamp group, a first input end of the MOS transistor group is connected with the LCD backlight drive IC, a second input end of the MOS transistor group is connected with the LED lamp group, and the output end of the MOS transistor group is grounded. By simply controlling the LCD backlight drive IC to output a suitable PWM (pulse width modulation) signal, the current level of the LED lamp group can be adjusted continuously to ensure smooth transition in brightness of the LCD backlight, thereby avoiding EMI (electro magnetic interference). Moreover, the current control module has the characteristics of simple structure, low cost and the like.
Description
Technical field
The utility model relates to the control device of the LCD backlight illumination of electronic product, is specifically related to mobile terminal LCD current control module backlight.
Background technology
LCD (the Liquid Crystal Display of present portable terminal, LCDs) backlight generally adopts parallel LED (Light Emitting Diode, light emitting diode) lamp, these LED lamps need to control by a drive IC (integrated circuit, integrated circuit) brightness of LCD backlight usually.
Traditional parallel LCD backlight drive IC generally has an enable port, and the user can be by carrying PWM (Pulse Width Modulation, pulse-length modulation) signal to reach the purpose of regulating the LED-backlit electric current to this enable port.This kind mode can make backlight drive IC frequent starting and close, the as easy as rolling off a log like this EMI that causes disturbs (Electro magnetic Interference, electromagnetic interference (EMI)), and the load variations that causes of frequent switch I C make output voltage unstable and cause LED backlight that problems such as flicker take place.
At present, it is to adopt to have I2C bus (Inter-Integrated Circuit that industry also has some practices, integrated circuit) or rapid pulse towards the backlight drive IC of the mode Control current of number output, this class IC can not cause frequent starting and closing problem, but brightness degree is limited, and brightness degree fixes, and the dirigibility of regulating brightness is very poor, when realizing some LCD backlight illumination fade effect, can not realize seamlessly transitting.
Thereby prior art is still waiting to improve and improve.
The utility model content
In view of above-mentioned the deficiencies in the prior art part, the current control module that provides mobile terminal LCD backlight is provided the purpose of this utility model, can regulate the current class of backlight continuously.
In order to achieve the above object, the utility model has been taked following technical scheme:
The current control module that mobile terminal LCD is backlight, described current control module are arranged between LCD backlight drive IC and the LCD LED lamp backlight group, and wherein, described current control module comprises charge pump and metal-oxide-semiconductor group; The input end of described charge pump is connected with power supply, and output terminal is connected with described LED lamp group; The first input end of described metal-oxide-semiconductor group is connected with LCD backlight drive IC, and second input end is connected the output head grounding of metal-oxide-semiconductor group with described LED lamp group.
The current control module that described mobile terminal LCD is backlight wherein, is provided with a filtering circuit between the first input end of the pwm signal output terminal of described LCD backlight drive IC and described metal-oxide-semiconductor group.
The current control module that described mobile terminal LCD is backlight, wherein, described metal-oxide-semiconductor group comprises first metal-oxide-semiconductor, second metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor, described LED lamp group comprises a LED lamp, the 2nd LED lamp, the 3rd LED lamp and the 4th LED lamp; Wherein
The grid of described first metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of a LED lamp, source ground;
The grid of described second metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 2nd LED lamp, source ground;
The grid of described the 3rd metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 3rd LED lamp, source ground;
The grid of described the 4th metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 4th LED lamp, source ground.
The current control module that described mobile terminal LCD is backlight, wherein, described filtering circuit comprises the resistance and first electric capacity, described resistance string is associated between the first input end of the pwm signal output terminal of described LCD backlight drive IC and described metal-oxide-semiconductor group, one end of described first electric capacity is connected with described resistance, other end ground connection.
The current control module that described mobile terminal LCD is backlight, wherein, described charge pump is provided with one second electric capacity.
The current control module that described mobile terminal LCD is backlight, wherein, described power supply is a battery.
The current control module that described mobile terminal LCD is backlight, wherein, described first metal-oxide-semiconductor, second metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor are the N-channel MOS pipe.
The current control module that the mobile terminal LCD that the utility model provides is backlight, this current control module is arranged between LCD backlight drive IC and the LCD LED lamp backlight group, current control module has adopted the charge pump that supply voltage is raise and has controlled the metal-oxide-semiconductor group that flows through LED lamp group size of current, only need by the suitable pwm signal of control LCD backlight drive IC output, just can realize regulating continuously the current class of LED lamp group, make LCD brightness smooth excessiveness backlight, avoided the EMI interference; Characteristics such as while current control module of the present utility model also has simple in structure, and cost is low.
Description of drawings
Fig. 1 is the structured flowchart that the utility model LCD backlight illumination is regulated;
Fig. 2 is the schematic block circuit diagram of the utility model current control module;
Fig. 3 is the circuit diagram of the utility model current control module.
Embodiment
The utility model provides mobile terminal LCD current control module backlight, this current control module is connected between the input end of the pwm signal output terminal of LCD backlight drive IC and LCD LED lamp backlight group, be used for regulating continuously the electric current that flows through LCD LED lamp backlight group, thereby realize LCD backlight illumination smooth excessiveness, and can not produce the EMI interference.
For making the purpose of this utility model, technical scheme and effect clearer, clear and definite, below with reference to accompanying drawing and give an actual example the utility model is further described.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.
See also Fig. 1, the mobile terminal LCD that the utility model provides current control module 110 backlight is connected between the LED lamp group 120 and LCD backlight drive IC130 of portable terminal, be used to regulate the current class that flows through mobile terminal LCD LED lamp backlight, thereby realize the smooth excessiveness of LCD backlight illumination.
See also Fig. 2 and Fig. 3, current control module 100 of the present utility model can be arranged to a chip that is used for the Control current size, so the alleged current control module of the utility model also can be called the Current Control chip.Comprise charge pump 111 and metal-oxide-semiconductor (metal oxid semiconductor, field effect transistor) group 112 at this chip internal.
Wherein, the first input end of described charge pump 111 is connected with power supply Vbat, second input end grounding, and the output terminal of described charge pump 111 is connected with the input end of LED lamp group 120.This charge pump 111 is mainly used in to be exported after voltage with Current Control chip input end is elevated to certain voltage, gives LED lamp group 120 power supplies.
Because charge pump is given the power supply of LED lamp group, and charge pump is by power supply Vbat power supply, so monoblock chip (being current control module) is powered by power supply Vbat.In the present embodiment, described power supply Vbat is the battery of portable terminal, and charge pump 111 is provided with second capacitor C 2, and this second capacitor C 2 is connected with two Wiring ports of charge pump, mainly shields in this circuit.Also can think the peripheral electron element that this second capacitor C 2 is described Current Control chips herein, second capacitor C 2 is connected on two pins of this Current Control chip.
Described metal-oxide-semiconductor group 112 is mainly used in the size that the electric current of LED lamp group 120 is flow through in control, the first input end of this metal-oxide-semiconductor group 112 is connected with the pwm signal output terminal of LCD backlight drive IC130, second input end is connected the output head grounding of metal-oxide-semiconductor group 112 with the output terminal of described LED lamp group 120.
Wherein, described LCD backlight drive IC130 controls the voltage on the first input end that is added in the metal-oxide-semiconductor group by its enable port output pwm signal.
The utility model has changed the mode of traditional pure digi-tal control LCD backlight illumination, has adopted the mode of digital simulation combination.Please continue to consult Fig. 2, between the first input end of the pwm signal output terminal of described LCD backlight drive IC130 and metal-oxide-semiconductor group 112, be provided with a filtering circuit 140.
Described filtering circuit 140 comprises the resistance R 1 and first capacitor C 1, described resistance R 1 is connected between the first input end of the pwm signal output terminal of described LCD backlight drive IC130 and metal-oxide-semiconductor group 112, the input end of described first capacitor C 1 connects the output terminal of resistance R 1, the output head grounding of first capacitor C 1.
In the present embodiment, produce DC voltage after the backlight control pwm signal process resistance R 1 of LCD backlight drive IC130 output, 1 filtering of first capacitor C, the digital signal of LCD backlight drive IC130 output is converted to analog level, make metal-oxide-semiconductor group 112 be operated in the saturation region, flow through the purpose of the electric current of LED lamp group 120 to reach control.
In the present embodiment, metal-oxide-semiconductor quantity should be consistent with the quantity of LED lamp in the LED lamp group 120 in the metal-oxide-semiconductor group 112, like this can be by LED lamp of a metal-oxide-semiconductor control, and wherein, the quantity of metal-oxide-semiconductor and LED lamp can be provided with according to actual needs.
See also Fig. 3, it is the circuit diagram of current control module, and described metal-oxide-semiconductor group 112 comprises 4 metal-oxide-semiconductors, is respectively the first metal-oxide-semiconductor M1, the second metal-oxide-semiconductor M2, the 3rd metal-oxide-semiconductor M3 and the 4th metal-oxide-semiconductor M4, and these 4 metal-oxide-semiconductors all adopt the N-channel MOS pipe.
Correspondingly, LED lamp group 120 comprises 4 LED lamps, is respectively a LED lamp D1, the 2nd LED lamp D2, the 3rd LED lamp D3 and the 4th LED lamp D4.
Wherein, the grid of the described first metal-oxide-semiconductor M1 connects the pwm signal output terminal of LCD backlight drive IC130, and the drain electrode of the described first metal-oxide-semiconductor M1 connects a LED lamp D1 negative electrode, the source ground of the first metal-oxide-semiconductor M1.
The grid of the described second metal-oxide-semiconductor M2 connects the pwm signal output terminal of LCD backlight drive IC130, and the drain electrode of the described second metal-oxide-semiconductor M2 connects the 2nd LED lamp D2 negative electrode, the source ground of the second metal-oxide-semiconductor M2.
The grid of described the 3rd metal-oxide-semiconductor M3 connects the pwm signal output terminal of LCD backlight drive IC130, and the drain electrode of described the 3rd metal-oxide-semiconductor M3 connects the 3rd LED lamp D3 negative electrode, the source ground of the 3rd metal-oxide-semiconductor M3.
The grid of described the 4th metal-oxide-semiconductor M4 connects the pwm signal output terminal of LCD backlight drive IC130, and the drain electrode of described the 4th metal-oxide-semiconductor M4 connects the 4th LED lamp D4 negative electrode, the source ground of the 4th metal-oxide-semiconductor M4.
Below the principle of work of the utility model current control module (being the Current Control chip) is described in detail:
Please continue to consult Fig. 3, the Current Control chip is powered by power supply Vbat (battery), the main effect of charge pump 111 is that the voltage with power supply Vbat is elevated to certain voltage, and from the output of the Vout port of Current Control chip, the effect of metal-oxide-semiconductor group 112 is electric currents that the LED lamp group of chip exterior is flow through in control.
The backlight control pwm signal is provided by the pwm signal output terminal of LCD backlight drive IC130, the DC voltage that produces after 1 filtering of pwm signal process resistance R 1, the first capacitor C.The dutycycle of supposing pwm signal is D, and the voltage amplitude of pwm signal is V, and then the control voltage that obtains at the Va of Current Control chip end is V * D.
The utility model embodiment is to make the metal-oxide-semiconductor in the metal-oxide-semiconductor group 112 be operated in the saturation region, and metal-oxide-semiconductor group 112 at the electric current of saturation region is:
The condition that above-mentioned formula is set up is: Vds＞Vgs-Vth, and wherein, μ is semi-conductive electronics rate travel,
The electric capacity of seeing into for the GATE of metal-oxide-semiconductor end (grid).V
GsBe the GATE (grid) of metal-oxide-semiconductor and the voltage between the SOURCE (source electrode), promptly Current Control chip Va holds the aanalogvoltage of input, V
ThThreshold voltage for metal-oxide-semiconductor.
Parameter in the above-mentioned formula is except Vgs, and other parameters all by the technology decision of metal-oxide-semiconductor own, be fixed value, so electric current I only change with Vgs.
At this, the output voltage V out that supposes the electric current chip is more than 5V, then can reach about 1.8V at DRAIN of metal-oxide-semiconductor (drain electrode) and SOURCE (source electrode) both end voltage Vds, this moment is by the pwm signal of control LCD backlight drive IC, make aanalogvoltage on the Va control pin below 1.8V, thereby, satisfy the condition of Vds＞Vgs-Vth.Metal-oxide-semiconductor just can be operated in the saturation region like this, and the electric current that flows through metal-oxide-semiconductor just can be controlled by Vgs, just by the pwm signal of LCD backlight drive output, controls through the aanalogvoltage of filtering circuit conversion.
The utility model utilizes filtering circuit that the PWM digital signal of LCD backlight drive IC is converted to analog level, and make the metal-oxide-semiconductor of Current Control chip internal be operated in the saturation region, to reach purpose with the electric current I ds of the grid of metal-oxide-semiconductor and the control of the voltage Vgs between source electrode metal-oxide-semiconductor.Design need not much changes to this backlight drive IC for mobile phone hardware, only needs to get final product by the suitable pwm signal of software control LCD backlight drive IC output of portable terminal.
In sum, the current control module that the mobile terminal LCD that the utility model provides is backlight, this current control module is arranged between LCD backlight drive IC and the LCD LED lamp backlight group, current control module has adopted the charge pump that supply voltage is raise and has controlled the metal-oxide-semiconductor group that flows through LED lamp group size of current, only need by the suitable pwm signal of control LCD backlight drive IC output, just can realize regulating continuously the current class of LED lamp group, make LCD brightness smooth excessiveness backlight, avoided the EMI interference; Characteristics such as while current control module of the present utility model also has simple in structure, and cost is low.
Be understandable that; for those of ordinary skills; can be equal to replacement or change according to the technical solution of the utility model and utility model design thereof, and all these changes or replacement all should belong to the protection domain of the appended claim of the utility model.
Claims (7)
1. current control module that mobile terminal LCD is backlight, described current control module is arranged between LCD backlight drive IC and the LCD LED lamp backlight group, it is characterized in that described current control module comprises charge pump and metal-oxide-semiconductor group; The input end of described charge pump is connected with power supply, and output terminal is connected with described LED lamp group; The first input end of described metal-oxide-semiconductor group is connected with LCD backlight drive IC, and second input end is connected the output head grounding of metal-oxide-semiconductor group with described LED lamp group.
2. mobile terminal LCD according to claim 1 current control module backlight is characterized in that, is provided with a filtering circuit between the first input end of the pwm signal output terminal of described LCD backlight drive IC and described metal-oxide-semiconductor group.
3. mobile terminal LCD according to claim 1 current control module backlight, it is characterized in that, described metal-oxide-semiconductor group comprises first metal-oxide-semiconductor, second metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor, and described LED lamp group comprises a LED lamp, the 2nd LED lamp, the 3rd LED lamp and the 4th LED lamp; Wherein
The grid of described first metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of a LED lamp, source ground;
The grid of described second metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 2nd LED lamp, source ground;
The grid of described the 3rd metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 3rd LED lamp, source ground;
The grid of described the 4th metal-oxide-semiconductor connects the pwm signal output terminal of LCD backlight drive IC, and drain electrode connects the negative electrode of the 4th LED lamp, source ground.
4. mobile terminal LCD according to claim 2 current control module backlight, it is characterized in that, described filtering circuit comprises the resistance and first electric capacity, described resistance string is associated between the first input end of the pwm signal output terminal of described LCD backlight drive IC and described metal-oxide-semiconductor group, one end of described first electric capacity is connected with described resistance, other end ground connection.
5. mobile terminal LCD according to claim 1 current control module backlight is characterized in that described charge pump is provided with one second electric capacity.
6. mobile terminal LCD according to claim 1 current control module backlight is characterized in that described power supply is a battery.
7. mobile terminal LCD according to claim 1 current control module backlight is characterized in that described first metal-oxide-semiconductor, second metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor are the N-channel MOS pipe.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201020287318XU CN201804537U (en) | 2010-08-02 | 2010-08-02 | Current control module of LCD (liquid crystal display) backlight of mobile terminal |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201020287318XU CN201804537U (en) | 2010-08-02 | 2010-08-02 | Current control module of LCD (liquid crystal display) backlight of mobile terminal |
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| CN201804537U true CN201804537U (en) | 2011-04-20 |
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| CN201020287318XU Expired - Fee Related CN201804537U (en) | 2010-08-02 | 2010-08-02 | Current control module of LCD (liquid crystal display) backlight of mobile terminal |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102800298A (en) * | 2012-09-11 | 2012-11-28 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit and LED backlight driving method |
| CN103050088A (en) * | 2011-10-11 | 2013-04-17 | 联芯科技有限公司 | Terminal and LCD (Liquid Crystal Display) backlight driving method thereof |
-
2010
- 2010-08-02 CN CN201020287318XU patent/CN201804537U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103050088A (en) * | 2011-10-11 | 2013-04-17 | 联芯科技有限公司 | Terminal and LCD (Liquid Crystal Display) backlight driving method thereof |
| CN102800298A (en) * | 2012-09-11 | 2012-11-28 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit and LED backlight driving method |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110420 Termination date: 20130802 |