CN203102817U - LED (Light-Emitted Diode) backlight driving circuit, backlight module and liquid crystal display device - Google Patents
LED (Light-Emitted Diode) backlight driving circuit, backlight module and liquid crystal display device Download PDFInfo
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- CN203102817U CN203102817U CN 201320116754 CN201320116754U CN203102817U CN 203102817 U CN203102817 U CN 203102817U CN 201320116754 CN201320116754 CN 201320116754 CN 201320116754 U CN201320116754 U CN 201320116754U CN 203102817 U CN203102817 U CN 203102817U
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Abstract
The utility model discloses an LED (Light-Emitted Diode) backlight driving circuit, a backlight module and a liquid crystal display device. The LED backlight driving circuit comprises a booster module, wherein the booster module comprises a voltage regulating controllable switch, the control end of the voltage regulating controllable switch is coupled with a constant current driving module, the backlight driving module further comprises a step-down transformer and a current detecting resistor, the voltage regulating controllable switch is grounded through the primary side of the transformer, the current detecting resistor is connected to the secondary side of the transformer in series, and the voltage signal of the current detecting resistor is fed back to the constant current driving module. The problem of difficult selection of the current detecting resistance value is solved.
Description
Technical field
The utility model relates to field of liquid crystal display, in particular, relates to a kind of LED-backlit driving circuit, module backlight and liquid crystal indicator.
Background technology
Liquid crystal indicator comprises liquid crystal panel and module backlight, and existing module backlight adopts LED as light source more, and is supporting, needs design LED corresponding backlight driving circuit.Existing LED-backlit driving circuit as shown in Figure 1, during metal-oxide-semiconductor Q1 conducting, inductive current rises, when Q1 turn-offs, inductive current descends, the inductive current waveform is a triangular wave, the inductive current maximal value depends on the ON time of metal-oxide-semiconductor in one-period and the size of output power, and output power is big more, and the metal-oxide-semiconductor ON time is long more, the inductive current maximal value is just big more, after the inductive current maximal value had surpassed the inductance saturation current, inductance value descended, and inductance is more little to the inhibition of electric current, electric current sharply rises, and can cause fuse melting (fuse) and metal-oxide-semiconductor to burn out.
LED constant-current driving IC has a feedback pin CS; about 0.4～the 0.5V of its detecting voltage; by choosing of external impressed current detecting resistance value; can control the lowest high-current value that flows through inductance; when the voltage on the feedback pin CS greater than detecting during voltage; IC starts protection, turn-offs metal-oxide-semiconductor Q1, and inductive current no longer rises.IC producer considers that the power consumption that Chip-R can bear is smaller, so with the detecting voltage of feedback pin CS set less, because the current value on the inductance is bigger, the detecting voltage of feedback pin CS and the ratio of inductive current, be the required current sense resistance value of choosing, the resistance that obtains is generally tens M Ω, and such resistance is of little use, and price is also more expensive; After many resistance parallel connections with other resistance, not only cost is higher, also is difficult to obtain suitable current detecting resistance value.
The utility model content
Technical problem to be solved in the utility model provides a kind of current sense resistance value that solves and chooses the LED-backlit driving circuit of difficult problem, module backlight and liquid crystal indicator.
The purpose of this utility model is achieved through the following technical solutions:
A kind of LED-backlit driving circuit, comprise boost module, described boost module comprises the pressure regulation gate-controlled switch, the control end of described pressure regulation gate-controlled switch is coupled with constant-current driven module, described backlight drive circuit also comprises step-down transformer and current sense resistance, described pressure regulation gate-controlled switch is by the former edge joint ground of transformer, and described current sense resistance string is received the secondary of described transformer;
The voltage signal of described current sense resistance feeds back to described constant-current driven module.
Further, described constant-current driven module comprises comparison module, and the voltage signal of described current sense resistance is coupled to described comparison module.Adopt comparison module to carry out voltage ratio, regulate the output of control signal by fiducial value, scheme is simple, helps simplifying circuit structure.
Further, described comparison module comprises comparer, and the input end in the same way of described comparer is coupled to the reference signal of voltage constant; Reverse input end is coupled to the voltage signal of described current sense resistance.This is a kind of concrete comparison module circuit structure.
Further, described boost module comprises inductance, commutation diode; Described inductance one end connects the positive pole of power supply, and the other end connects the positive pole of commutation diode, and the negative pole of described commutation diode connects the LED lamp bar of described LED-backlit driving circuit.This is a kind of concrete boost circuit structure.
Further, be connected with electric capacity between the negative pole of the negative pole of described commutation diode and power supply.Electric capacity can storing electricity, gives the power supply of LED lamp bar in the gate-controlled switch conducting, keeps the demonstration of LED lamp bar.
Further, described pressure regulation gate-controlled switch is coupled to the positive pole of described commutation diode.Be that the pressure regulation gate-controlled switch is connected between inductance and the commutation diode.When the conducting of pressure regulation gate-controlled switch, inductive energy storage, its polarity is reverse with electric power polarity; When the pressure regulation gate-controlled switch is closed, inductive discharge, polarity and power supply in the same way, the stack of both voltages forms the effect of boosting.
Further, described pressure regulation gate-controlled switch is a field effect transistor.This is a kind of circuit form of concrete pressure regulation gate-controlled switch.
Further, described constant-current driven module comprises comparison module, and the voltage signal of described current sense resistance is coupled to described comparison module; Described comparison module comprises comparer, and the input end in the same way of described comparer is coupled to the reference signal of voltage constant; Reverse input end is coupled to the voltage signal of described current sense resistance; Described boost module comprises inductance, commutation diode; Described inductance one end connects the positive pole of power supply, and the other end connects the positive pole of commutation diode, and the negative pole of described commutation diode connects the LED lamp bar of described LED-backlit driving circuit; Be connected with electric capacity between the negative pole of described commutation diode and the negative pole of power supply; Described pressure regulation gate-controlled switch is coupled to the positive pole of described commutation diode; Described pressure regulation gate-controlled switch is a field effect transistor.This is a kind of circuit form of concrete LED-backlit driving circuit.
A kind of module backlight comprises LED-backlit driving circuit described in the utility model.
A kind of liquid crystal indicator comprises module backlight described in the utility model.
The utility model is owing to adopted step-down transformer, can connect current sense resistance later on again by voltage scaled down with pressure regulation gate-controlled switch place branch road, so just the big current conversion that flows through the pressure regulation gate-controlled switch can be become the little electric current of secondary coil, the ratio of Zhen Ce voltage signal and little electric current can be bigger like this, can choose resistance commonly used as current sense resistance, reduced cost, solved the current sense resistance value and chosen difficult problem.
Description of drawings
Fig. 1 is existing a kind of backlight drive circuit synoptic diagram;
Fig. 2 is the utility model embodiment principle schematic.
Embodiment
The utility model discloses a kind of liquid crystal indicator.Liquid crystal indicator comprises liquid crystal panel and module backlight, and module backlight comprises LED lamp bar and LED-backlit driving circuit.The LED-backlit driving circuit comprises boost module, boost module comprises the pressure regulation gate-controlled switch, the control end of pressure regulation gate-controlled switch is coupled with constant-current driven module, backlight drive circuit also comprises step-down transformer and current sense resistance, the pressure regulation gate-controlled switch is by the former edge joint ground of transformer, and the current sense resistance string is received the secondary of transformer; The voltage signal of current sense resistance feeds back to constant-current driven module.
The utility model is owing to adopted step-down transformer, can connect current sense resistance later on again by voltage scaled down with pressure regulation gate-controlled switch place branch road, so just the big current conversion that flows through the pressure regulation gate-controlled switch can be become the little electric current of secondary coil, the ratio of Zhen Ce voltage signal and little electric current can be bigger like this, can choose resistance commonly used as current sense resistance, solve the current sense resistance value and chosen difficult problem.
The utility model is described in further detail below in conjunction with accompanying drawing and preferred embodiment.
Referring to Fig. 2, the LED-backlit driving circuit of present embodiment comprises boost module, boost module comprises pressure regulation gate-controlled switch Q1, the control end of pressure regulation gate-controlled switch Q1 is coupled with constant-current driven module, backlight drive circuit also comprises step-down transformer T1 and current sense resistance R 1, pressure regulation gate-controlled switch Q1 is by the former edge joint ground of transformer T1, and current sense resistance R 1 is concatenated into the secondary of transformer T1; The voltage signal of current sense resistance R 1 feeds back to constant-current driven module.Boost module comprises inductance L 1, commutation diode D1; Inductance L 1 one ends connect the positive pole of 24V power supply, and the other end connects the positive pole of commutation diode D1, and the negative pole of commutation diode D1 connects the LED lamp bar of LED-backlit driving circuit.Certainly, power supply of the present utility model can also be selected the power supply of other electric pressures such as 12V, 36V for use.
Constant-current driven module comprises comparison module, and comparison module can be selected comparer OP1 such as operational amplifier for use, and the input end in the same way of comparer OP1 is coupled to the reference signal V of voltage constant; Reverse input end is coupled to the voltage signal of current sense resistance R 1; After comparer OP1 compared voltage signal and reference signal V, output drive signal was to the control end of pressure regulation gate-controlled switch Q1.Adopt comparison module to carry out voltage ratio, regulate the output of control signal by fiducial value, scheme is simple, helps simplifying circuit structure.
Pressure regulation gate-controlled switch Q1 is coupled to the positive pole of commutation diode D1, and promptly pressure regulation gate-controlled switch Q1 is connected between inductance L 1 and the commutation diode D1; Pressure regulation gate-controlled switch Q1 can select the semiconductor devices that comprises field effect transistor for use.When pressure regulation gate-controlled switch Q1 conducting, inductance L 1 energy storage, its polarity is reverse with electric power polarity; When pressure regulation gate-controlled switch Q1 closes, inductance L 1 discharge, polarity and power supply in the same way, both voltages stacks, the effect that formation is boosted.
Be connected with capacitor C 1 between the negative pole of commutation diode D1 and the negative pole of power supply; Capacitor C 1 can storing electricity, gives the power supply of LED lamp bar in the gate-controlled switch conducting, keeps the demonstration of LED lamp bar.
Above content be in conjunction with concrete preferred implementation to further describing that the utility model is done, can not assert that concrete enforcement of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field, under the prerequisite that does not break away from the utility model design, can also make some simple deduction or replace, all should be considered as belonging to protection domain of the present utility model.
Claims (10)
1. LED-backlit driving circuit, comprise boost module, described boost module comprises the pressure regulation gate-controlled switch, the control end of described pressure regulation gate-controlled switch is coupled with constant-current driven module, it is characterized in that, described backlight drive circuit also comprises step-down transformer and current sense resistance, and described pressure regulation gate-controlled switch is by the former edge joint ground of transformer, and described current sense resistance string is received the secondary of described transformer; The voltage signal of described current sense resistance feeds back to described constant-current driven module.
2. LED-backlit driving circuit as claimed in claim 1 is characterized in that described constant-current driven module comprises comparison module, and the voltage signal of described current sense resistance is coupled to described comparison module.
3. LED-backlit driving circuit as claimed in claim 2 is characterized in that described comparison module comprises comparer, and the input end in the same way of described comparer is coupled to the reference signal of voltage constant; Reverse input end is coupled to the voltage signal of described current sense resistance.
4. LED-backlit driving circuit as claimed in claim 1 is characterized in that described boost module comprises inductance, commutation diode; Described inductance one end connects the positive pole of power supply, and the other end connects the positive pole of commutation diode, and the negative pole of described commutation diode connects the LED lamp bar of described LED-backlit driving circuit.
5. LED-backlit driving circuit as claimed in claim 4 is characterized in that, is connected with electric capacity between the negative pole of described commutation diode and the negative pole of power supply.
6. LED-backlit driving circuit as claimed in claim 4 is characterized in that described pressure regulation gate-controlled switch is coupled to the positive pole of described commutation diode.
7. LED-backlit driving circuit as claimed in claim 1 is characterized in that, described pressure regulation gate-controlled switch is a field effect transistor.
8. LED-backlit driving circuit as claimed in claim 1 is characterized in that described constant-current driven module comprises comparison module, and the voltage signal of described current sense resistance is coupled to described comparison module; Described comparison module comprises comparer, and the input end in the same way of described comparer is coupled to the reference signal of voltage constant; Reverse input end is coupled to the voltage signal of described current sense resistance; Described boost module comprises inductance, commutation diode; Described inductance one end connects the positive pole of power supply, and the other end connects the positive pole of commutation diode, and the negative pole of described commutation diode connects the LED lamp bar of described LED-backlit driving circuit; Be connected with electric capacity between the negative pole of described commutation diode and the negative pole of power supply; Described pressure regulation gate-controlled switch is coupled to the positive pole of described commutation diode; Described pressure regulation gate-controlled switch is a field effect transistor.
9. a module backlight comprises as the arbitrary described LED-backlit driving circuit of claim 1～8.
10. a liquid crystal indicator comprises module backlight as claimed in claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116754 CN203102817U (en) | 2013-03-14 | 2013-03-14 | LED (Light-Emitted Diode) backlight driving circuit, backlight module and liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116754 CN203102817U (en) | 2013-03-14 | 2013-03-14 | LED (Light-Emitted Diode) backlight driving circuit, backlight module and liquid crystal display device |
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| Publication Number | Publication Date |
|---|---|
| CN203102817U true CN203102817U (en) | 2013-07-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320116754 Expired - Lifetime CN203102817U (en) | 2013-03-14 | 2013-03-14 | LED (Light-Emitted Diode) backlight driving circuit, backlight module and liquid crystal display device |
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| CN (1) | CN203102817U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103745701A (en) * | 2013-12-30 | 2014-04-23 | 深圳市华星光电技术有限公司 | Flyback boosting circuit, LED (light emitting diode) backlight driving circuit and liquid crystal display |
| WO2015024277A1 (en) * | 2013-08-21 | 2015-02-26 | 深圳市华星光电技术有限公司 | Backlight drive circuit, electronic device and backlight drive method |
-
2013
- 2013-03-14 CN CN 201320116754 patent/CN203102817U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015024277A1 (en) * | 2013-08-21 | 2015-02-26 | 深圳市华星光电技术有限公司 | Backlight drive circuit, electronic device and backlight drive method |
| CN103745701A (en) * | 2013-12-30 | 2014-04-23 | 深圳市华星光电技术有限公司 | Flyback boosting circuit, LED (light emitting diode) backlight driving circuit and liquid crystal display |
| CN103745701B (en) * | 2013-12-30 | 2016-05-04 | 深圳市华星光电技术有限公司 | Inverse-excitation type booster circuit, LED-backlit drive circuit and liquid crystal display |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20130731 |