CN203276795U - LED for backlight display - Google Patents

Abstract

The utility model provides an LED for backlight display. The LED for backlight display includes an LED illuminant and an LED driving circuit. The LED illuminant is located behind a backlight display screen. The LED driving circuit includes: a boundary-type voltage-boosting power factor correction circuit, an active-clamping forward converter, and a high-low-limit constant current pulse width modulation driving light modulation circuit, which are connected in sequence. Luminescence characteristics of a light emitting diode (LED) are analyzed and current control is pointed out to be an optimal method for LED brightness modulation, taking a liquid crystal display (LCD) backlight module as an application background. An LED driving light modulation circuit with a three level structure is designed to obtain a higher luminescence efficiency and a better light modulation effect. It is shows by experiments that, by utilizing the designed LED driving circuit, a power factor of a system is increased, and drifts of LED main wavelength and color coordinate are reduced, so that luminance of the LED can be controlled effectively.

Description

Demonstration LED backlight

Technical field

The utility model relates to display technique field, LED-backlit source, more specifically, relates to a kind of demonstration backlight LED equipment.

Background technology

At present traditional along with the progress of society and the development of technology, the display device that the characteristics such as the display device of LED (light-emittingdiode Light Emitting Diode) backlight is high with its reliability, long service life, adaptive capacity to environment is strong, cost performance is reasonable, use cost is low substitute traditional C CFL (cathode fluorescent tube Cold CathodeFluorescent Lamp) backlight gradually becomes rapidly the main product that large flat shows, is widely used in field of information display.The huge market demand impels liquid crystal panel manufacturer and national governments activity investments to set up the LED product line of a new generation, in this case, satisfies 55 inches and following liquid crystal panel 8.5 generation production line and builds like the mushrooms after rain.When various countries actively build 8.5 generation lines, with leading panel vendors such as Korea S's Samsung and Japanese Sharps, especially actively to higher line generation---can satisfy the 10 generations line investment that 65 inches and above HDTV, exhibition room display and billboard etc. are used.

The backing structure of 55 inches of traditional LED-backlit source and following display device generally has following two kinds:

1, downward back photo structure

Although on principle, LED array can be made infinity, but the existence due to air layer d, increased undoubtedly the thickness of whole display, because needing a large number of LED, this class display does support simultaneously, also increased from another point of view the energy consumption of display, be unfavorable for the reduction of display use cost, therefore this backing structure can't be made superhuge display device.

2, side entrance back structure

But because present LED brightness range is limit, the light guide plate width also must be restricted, and be positioned at the periphery of display due to this type of design LED luminescence unit, therefore be difficult to fundamentally improve the dynamic contrast of whole display, thereby make this backing structure can't make superhuge display device equally.

Thus, need a kind of LED of design can accomplish 65 inches even larger display devices as backlight, size, and if this display device satisfy the performance requirement of low cost, low energy consumption, high brightness and contrast.

The utility model content

For the problems referred to above, the utility model provides demonstration LED backlight, it is characterized in that: described LED comprises the LED luminophor, LED drive circuit, described LED luminous body position is after backlit display screen, and described LED drive circuit comprises: connect in turn: Boundary-Type step-up type power factor correction circuit, active clamping forward converter, the spacing constant current width modulation of height drive light adjusting circuit.

The technique scheme of utilizing the utility model to provide, display device can be accomplished infinity, ultra-thin in theory, and high according to the LED-backlit source display device brightness that the utility model is made, cost is low, dynamic contrast to, energy-conservation, the utility model adopts LED as backlight, go for 65 inches and above liquid crystal display, can be widely used in HDTV, show that Room display and billboard etc. need the display device of high definition, giant-screen.

Description of drawings

Describe in more detail exemplary embodiment of the present utility model by the reference accompanying drawing, above and other aspect of the present utility model and advantage will become and more be readily clear of, in the accompanying drawings:

Fig. 1 is demonstration backlight LED cross-sectional view of the present utility model.

Fig. 2 is demonstration backlight LED drive circuit functional-block diagram of the present utility model;

Fig. 3 is the circuit theory diagrams that Boundary-Type step-up type power factor correction circuit in LED drive circuit is used in demonstration backlight of the present utility model;

Fig. 4 is the circuit theory diagrams that active clamping forward converter in LED drive circuit is used in demonstration backlight of the present utility model;

Fig. 5 is that demonstration backlight of the present utility model drives the circuit theory diagrams of light adjusting circuit with the spacing constant current width modulation of height in LED drive circuit.

Embodiment

Hereinafter, now with reference to accompanying drawing, the utility model is described more fully, various embodiment shown in the drawings.Yet the utility model can be implemented in many different forms, and should not be interpreted as being confined to embodiment set forth herein.On the contrary, it will be thorough with completely providing these embodiment to make the disclosure, and scope of the present utility model is conveyed to those skilled in the art fully.

Hereinafter, exemplary embodiment of the present utility model is described with reference to the accompanying drawings in more detail.

With reference to accompanying drawing 1, Fig. 1 is demonstration backlight LED cross-sectional view of the present utility model, described LED comprises LED luminophor 1, LED drive circuit 3, described LED luminous body position is after backlit display screen 2, as Fig. 2 be demonstration backlight of the present utility model with as shown in the LED drive circuit functional-block diagram, described LED drive circuit comprises and connecting in turn: Boundary-Type step-up type power factor correction circuit, active clamping forward converter, the spacing constant current width modulation of height drive light adjusting circuit.

Fig. 3 is the circuit theory diagrams that Boundary-Type step-up type power factor correction circuit in LED drive circuit is used in demonstration backlight of the present utility model; The electric main of input obtains and inputs the sine voltage signal of synchronizeing with the form of electric resistance partial pressure after the full bridge rectifier rectification; The feedback signal of output voltage through after error amplifier therewith sine wave signal multiply each other in multiplier, obtain sinusoidal reference signal, as the foundation of switch closing time; During switch conduction, inductive current rises, and current sense resistance is compared the inductor current signal that obtains with sinusoidal wave reference voltage, switch cut-off when inductor current signal equals sinusoidal reference signal; After the switch cut-off, inductance begins to release energy, and this moment, the auxiliary winding of inductance began the zero current detecting, and when inductive current reduced to zero, the zero current circuit for detecting triggered flip-flop, and switch is conducting again, starts next cycle.

Fig. 4 is the circuit theory diagrams that active clamping forward converter in LED drive circuit is used in demonstration backlight of the present utility model; In transformer one side, main switch, auxiliary switch, clamping capacitance, resonant inductance are arranged, formed by two diodes, outputting inductance, output capacitance, loads in Circuit Fault on Secondary Transformer.Wherein main switch and auxiliary switch are MOSFETS, and resonant inductance equals outer coilloading and transformer primary side leakage inductance sum.

Fig. 5 is that demonstration backlight of the present utility model drives the circuit theory diagrams of light adjusting circuit with the spacing constant current width modulation of height in LED drive circuit.This circuit drives the control integration circuit by main switch, current transformer, current-limiting resistance, fly-wheel diode, energy storage inductor, light emitting diode module, output capacitance, flow control resistance, PWM and light adjusting circuit forms.

The above is only embodiment of the present utility model, is not limited to the utility model.The utility model can have various suitable changes and variation.All any modifications of doing, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model within spirit of the present utility model and principle.

Claims (4)

1. demonstration LED backlight is characterized in that:

Described LED comprises the LED luminophor, LED drive circuit, described LED luminous body position is after backlit display screen, and described LED drive circuit comprises in turn and to connect: Boundary-Type step-up type power factor correction circuit, active clamping forward converter, the spacing constant current width modulation of height drive light adjusting circuit.

2. demonstration LED backlight as claimed in claim 1 is characterized in that:

In described Boundary-Type step-up type power factor correction circuit, the electric main of input obtains and inputs the sine voltage signal of synchronizeing with the form of electric resistance partial pressure after the full bridge rectifier rectification; The feedback signal of output voltage through after error amplifier therewith sine wave signal multiply each other in multiplier, obtain sinusoidal reference signal, as the foundation of switch closing time; During switch conduction, inductive current rises, and current sense resistance is compared the inductor current signal that obtains with sinusoidal wave reference voltage, switch cut-off when inductor current signal equals sinusoidal reference signal; After the switch cut-off, inductance begins to release energy, and this moment, the auxiliary winding of inductance began the zero current detecting, and when inductive current reduced to zero, the zero current circuit for detecting triggered flip-flop, and switch is conducting again, starts next cycle.

3. demonstration LED backlight as claimed in claim 1 is characterized in that:

Described active clamping forward converter structure is as follows: in transformer one side, main switch, auxiliary switch, clamping capacitance, resonant inductance are arranged, be comprised of two diodes, outputting inductance, output capacitance, loads in Circuit Fault on Secondary Transformer; Wherein main switch and auxiliary switch are MOSFETS, and resonant inductance equals outer coilloading and transformer primary side leakage inductance sum.

4. demonstration LED backlight as described in claim 1-3 any one is characterized in that:

The spacing constant current width modulation of described height drives light adjusting circuit and is comprised of main switch, current transformer, current-limiting resistance, fly-wheel diode, energy storage inductor, light emitting diode module, output capacitance, flow control resistance, PWM driving control integration circuit and light adjusting circuit.

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