KR101202036B1 - Device for driving light emitting diode - Google Patents

Abstract

The present invention provides a driving device of a light emitting diode (LED). The driving apparatus of the LED according to an embodiment of the present invention includes a LED group to which a plurality of n LEDs are connected in series, a constant current providing unit to provide a constant current to the LED groups, and each of the LED groups. And a current path control signal providing unit which is connected in parallel to adjust the current path of the constant current and a current path control signal providing unit to the current path control signals, respectively, wherein the LED groups are connected in series.

Liquid Crystal Display, Backlight, Light Emitting Diode

Description

Device for driving light emitting diodes

1 is a configuration diagram of a driving circuit of a light emitting diode for backlight of a conventional liquid crystal display device.

2 is a configuration diagram of a driving device of a light emitting diode according to an embodiment of the present invention.

3 is a detailed configuration diagram illustrating a detailed configuration of a driving device of the light emitting diode of FIG. 2.

4 is a graph showing current path control signals of a driving device of a light emitting diode according to an embodiment of the present invention.

5 is a configuration diagram of a driving device of a light emitting diode according to another embodiment of the present invention.

6 is a circuit diagram illustrating a detailed configuration of the constant current providing unit of FIG. 5.

7 is a graph illustrating group activation signals of a driving device of a light emitting diode according to another embodiment of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

I100, I1000: Constant Current Provider

G100, G200, G300, G110, G210, G310: Light emitting diode group

S100, S200, S300: Current Path Control

S110, S210, S310: group activation unit

P100: current path control signal provider

P1000: Group Activation Signal Provider

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device of a light emitting diode (LED), and more particularly, to driving a plurality of light emitting diodes that can be used as a backlight of a flat panel display device such as a liquid crystal display device. By driving a plurality of light emitting diodes into a plurality of groups by using a single constant current providing circuit, the circuit structure of the driving device of the light emitting diode can be simplified and the cost of the driving device of the light emitting diode can be reduced. Relates to a device.

In today's information society, the role of electronic displays has become very important, and various electronic displays have been widely used in various industrial fields. In the electronic display device field, electronic display devices having new functions suitable for the demands of the information society, which have been continuously developed and diversified, are continuously being developed. In general, an electronic display device refers to a device that transmits various pieces of information to a human through vision. That is, the electronic display device refers to an electronic device that converts an electronic information signal output from various electronic devices into an optical information signal that can be recognized by a human vision, and is a device that plays a role of a bridge between humans and electronic devices. It can be said.

In such an electronic display device, when an optical information signal is displayed by a light emitting phenomenon, it is referred to as a light emitting display device, and when it is displayed by light modulation due to reflection, scattering, or interference phenomenon, it is called a light receiving display device. Light emitting displays, also called active display devices, include cathode ray tubes (CRTs), plasma display panels (PDPs), organic electroluminescent displays (OELDs), light emitting diodes ( Light Emitting Diode (LED) etc. can be mentioned. The light receiving display device, which is called a passive display device, may include a liquid crystal display (LCD), an electrophoretic image display (EPID), and the like.

Cathode ray tube display device, which is used for television and computer monitor, and has the longest history, has the highest market share in terms of economy, but has many disadvantages such as heavy weight, large volume and high power consumption. .

Recently, due to the rapid progress of semiconductor technology, there is a demand for a flat panel display device as an electronic display device suitable for a new environment in accordance with the trend of lowering and lowering power of various electronic devices and miniaturization, thinning, and lightening of electronic devices. It is rapidly increasing. Accordingly, flat panel display devices such as liquid crystal display (LCD), plasma display device (PDP), organic EL display (OELD), and the like are being developed. In particular, liquid crystal display devices having low power consumption and low driving voltage are drawing attention.

In the liquid crystal display, a liquid crystal material having an anisotropic dielectric constant is injected between an upper transparent insulating substrate on which a common electrode, a color filter, a black matrix, and the like are formed, and a lower transparent insulating substrate on which a switching element and a pixel electrode are formed. By applying different potentials to the electrodes and the common electrode, the intensity of the electric field formed in the liquid crystal material is adjusted to change the molecular arrangement of the liquid crystal material, thereby controlling the amount of light transmitted through the transparent insulating substrate to express a desired image. It is a display device. Since the liquid crystal display device is a light-receiving display device that does not emit light by itself, the liquid crystal display device uses a backlight installed on the back of the liquid crystal display panel for displaying an image to maintain uniform brightness of the entire screen. Cold cathode fluorescent lamps (CCFLs) and external electrode fluorescent lamps (EEFLs) are used as light sources of the backlights for liquid crystal displays, but the cold cathode fluorescent lamps or the external electrode fluorescent lamps may be used. In comparison, light emitting diodes (LEDs) have come into the spotlight as next-generation light sources that are excellent in energy saving and can be used semi-permanently.

Until now, the light emitting diode has been mainly used as a backlight light source of a small liquid crystal display device such as a mobile phone. However, as the luminance of the light emitting diode is improved, researches are being actively conducted to expand the backlight light source of a medium and large liquid crystal display device.

With reference to FIG. 1, the drive circuit of the backlight LED of the conventional liquid crystal display device is demonstrated. 1 is a configuration diagram of a driving circuit of a light emitting diode for backlight of a conventional liquid crystal display device.

The driving circuit of the light emitting diode for backlight of the conventional liquid crystal display includes constant current providing circuits 10, 20, 30, pulse width modulation signal providing circuit 40 and light emitting diodes D11 to D13, D21 to D23, and D31 to. D33). However, the driving circuit of the backlight LED of the conventional liquid crystal display includes three LEDs D11 to D13, D21 to D23, and D31 for dividing the backlight area into a plurality and independently adjusting the luminance of the backlight areas. To D33), separate constant current providing circuits 10, 20, and 30 are provided.

Therefore, in order to configure the driving circuit of the backlight LED of the conventional LCD, the constant current providing circuits 10, 20, and 30 must be provided in proportion to the number of divided backlight regions, so that the driving circuit of the LED is configured. There is a problem in that the number of necessary electronic elements is increased, and the price of the driving circuit of the light emitting diode is increased. In addition, a problem arises in that a wiring structure of a printed circuit board (PCB) on which a driving circuit of a light emitting diode is mounted is complicated.

Accordingly, an object of the present invention is to provide a driving device of a light emitting diode for driving a plurality of light emitting diodes that can be used as a backlight of a flat panel display device such as a liquid crystal display device. By dividing and driving a plurality of light emitting diodes into a plurality of groups, it is intended to provide a driving device of a light emitting diode that can simplify the circuit configuration of the driving device of the light emitting diode and reduce the cost of the driving device of the light emitting diode.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned above may be clearly understood by those skilled in the art from the following description. There will be.

According to an aspect of the present invention, there is provided a light emitting diode driving apparatus including: a plurality of light emitting diode groups, in which a plurality of light emitting diodes are connected in series; A constant current providing unit providing a constant current to the LED groups; Current path control units connected to each of the LED groups in parallel to adjust the current path of the constant current; And a current path control signal providing unit providing current path control signals to each of the current path control units, wherein the LED groups are connected in series, and the constant current providing unit is activated or deactivated by a pulse signal provided by the constant current controller. The switching element, a resistor for adjusting the magnitude of the current flowing through the switching element, and the electrical energy flowing through the switching element when the switching element is activated, and the electrical energy accumulated when the switching element is deactivated. It includes an inductor and a capacitor that emit into diode groups.

In the light emitting diode driving apparatus according to an embodiment of the present invention, it is preferable that the number n of the light emitting diodes of the light emitting diode groups is 2 or more and 15 or less.

In addition, the driving device of the light emitting diode according to the embodiment of the present invention is that the current path control units are composed of a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor (MOS FET)) or a bipolar junction transistor (BJT). desirable.

In addition, the driving device of the LED according to an embodiment of the present invention preferably further includes an overcurrent protection unit for suppressing the overcurrent flow to any one of the current path control unit.

In addition, in the driving apparatus of the LED according to the embodiment of the present invention, it is preferable that the overcurrent protection unit is composed of a Zener diode or a resistor.
In addition, the driving device of the light emitting diode according to an embodiment of the present invention preferably further comprises a zener diode for suppressing the overvoltage is applied to the constant current providing unit to the switching element.
In addition, in the driving device of the LED according to the embodiment of the present invention, it is preferable that the constant current controller adjusts the duty ratio of the pulse signal or the frequency of the pulse signal.

According to another aspect of the present invention, there is provided a light emitting diode driving apparatus including: a plurality of light emitting diode groups in which a plurality of light emitting diodes are connected in series; A constant current providing unit providing a constant current to the LED groups; Group activators connected in series to each of the LED groups to activate each of the LED groups; And a group activation signal providing unit providing group activation signals to each of the group activation units, wherein the LED groups are connected in parallel, and the constant current providing unit is activated or deactivated by a pulse signal provided by a constant current controller. A group of resistors configured to adjust a magnitude of a current flowing through the switching element, and accumulate electrical energy flowing through the switching element when the switching element is activated and accumulate the electrical energy accumulated when the switching element is deactivated. It includes inductors and capacitors that emit into the

In the light emitting diode driving apparatus according to another embodiment of the present invention, it is preferable that the number k of the light emitting diodes of the light emitting diode groups is 2 or more and 15 or less.

In addition, the driving device of the LED according to another embodiment of the present invention, it is preferable that the group activation portion is composed of a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor (MOS FET)) or a bipolar junction transistor (BJT). Do.

In addition, the driving apparatus of the LED according to another embodiment of the present invention is that the group activation signals are pulse signals, and the activation time of each of the LED groups is adjusted in proportion to the duty ratio of each of the group activation signals. It is preferable.

In addition, the driving device of the LED according to another embodiment of the present invention preferably further includes an overcurrent protection unit for suppressing the flow of overcurrent between each of the LED groups and each of the group activation unit.

In addition, in the driving apparatus of the LED according to another embodiment of the present invention, it is preferable that the overcurrent protection units are composed of a Zener diode or a resistor.
In addition, the driving device of the light emitting diode according to another embodiment of the present invention preferably further comprises a zener diode for suppressing the overvoltage is applied to the switching element.
In addition, in the driving apparatus of the LED according to another embodiment of the present invention, it is preferable that the constant current controller adjusts the duty ratio of the pulse signal or the frequency of the pulse signal.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention, and methods of achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. Like reference numerals refer to like elements throughout.

Referring to FIG. 2, a driving device of a light emitting diode according to an exemplary embodiment of the present invention will be described. 2 is a configuration diagram of a driving device of a light emitting diode according to an embodiment of the present invention.

As shown in FIG. 2, the driving apparatus of the LED according to the embodiment of the present invention includes the LED groups G100, G200, and G300, the constant current providing unit I100, and the current path adjusting units S100, S200, and S300. ) And a current path control signal providing unit P100.

In the light emitting diode groups G100, G200, and G300, a number n of light emitting diodes D101 to D103, D201 to D203, and D301 to D303 are connected in series, and the light emitting diode groups G100, G200, and G300 are connected in series. ) Are also connected in series. The constant current providing unit I100 provides a constant current to the LED groups G100, G200, and G300, and the current path control units S100, S200, and S300 are parallel to each of the LED groups G100, G200, and G300. It is connected to adjust the current path (current path) of the constant current provided by the constant current providing unit (I100). The current path control signal providing unit P100 provides the current path control signals PWM100, PWM200, and PWM300 which are pulse signals to the current path control units S100, S200, and S300, respectively.

3 and 4 will be described in more detail with respect to the driving device of the light emitting diode according to an embodiment of the present invention. 3 is a detailed configuration diagram illustrating a detailed configuration of a driving device of the light emitting diode of FIG. 2. 4 is a graph showing current path control signals of a driving device of a light emitting diode according to an embodiment of the present invention.

As shown in FIG. 3, the constant current providing unit I100 includes a constant current control unit I300, a voltage step-down circuit, and a resistor R100. Here, the voltage step-down circuit is for stepping down the power supply voltage VDD to a predetermined voltage, and a Buck-type voltage step-down circuit is widely used. Specifically, the buck type voltage step-down circuit may be composed of a switching element (Q100), an inductor (L100), a capacitor (C100), etc., the switching element (Q100) as a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET) Alternatively, a bipolar junction transistor (BJT) may be used.

A zener diode Z100 is connected between the first node N101 and the second node N102, and an inductor L100 is connected between the second node N102 and the third node N103. The capacitor C100 is connected between the first node N101 and the third node N103. The constant current controller I300 is connected between the fourth node N104 and the sixth node N106, and the switching element Q100 is connected between the second node N102, the fourth node N104, and the fifth node N105. ) Is connected, and a resistor R100 is connected between the fifth node N105 and the sixth node N106. The first group of light emitting diodes G100 is connected between the first node N101 and the seventh node N107, and the first current path control unit is further connected between the first node N101 and the seventh node N107. S100 is connected, and a plurality (n) of light emitting diodes D101 to D103 are connected in series to the first LED group G100. The second LED group G200 is connected between the seventh node N107 and the eighth node N108, and between the seventh node N107 and the eighth node N108, a second current path control unit ( S200 is connected, and a plurality (n) of light emitting diodes D201 to D203 are connected in series to the second LED group G200. The third LED group G300 is connected between the eighth node N108 and the third node N103, and the third current path controller may also be connected between the eighth node N108 and the third node N103. S300 is connected, and a plurality (n) of light emitting diodes D301 to D303 are connected in series to the third LED group G300.

Here, the power supply voltage VDD is applied to the first node N101, the ground voltage GND is applied to the sixth node N106, and the switching element Q100 is a pulse provided by the constant current controller I300. It is activated or deactivated by a signal. When the switching element Q100 is activated, electrical energy is accumulated in the inductor L100 and the capacitor C100. When the switching element Q100 is deactivated, energy stored in the inductor L100 and the capacitor C100 is stored. It is emitted to the light emitting diode groups G100, G200, and G300. In addition, the zener diode Z100 suppresses overvoltage from being applied to the switching element Q100, the resistor R100 adjusts the amount of current flowing through the switching element Q100, and the constant current controller I300 controls the switching element ( The power supply voltage VDD is stepped down to a predetermined voltage by adjusting the duty ratio of the pulse signal or the frequency of the pulse signal provided to the Q100. For example, when the driving device of the light emitting diode is used as a backlight for the liquid crystal display device, the power supply voltage VDD is provided with 24 V, and the voltage is 6 V to 18 V using the Buck type voltage step-down circuit. Step down to the light emitting diode groups (G100, G200, G300).

Meanwhile, the first current path controller S100 adjusts the current path of the constant current provided to the first LED group G100, and the second current path controller S200 is connected to the second LED group G200. The current path of the provided constant current is adjusted, and the third current path controller S300 adjusts the current path of the constant current provided by the constant current provider I100 to the third LED group G300. The current path controllers S100, S200, and S300 may be formed of a metal oxide semiconductor field effect transistor (MOS FET) or a bipolar junction transistor (BJT).

For example, as shown in FIG. 3, the current path controllers S100, S200, and S300 are configured as an NMOS FET, and as shown in FIG. 4, the first current path controller S100. The first current path control signal PWM100 is applied to the second current path control unit S200, and the second current path control signal PWM200 is applied to the third current path control unit S300. When the path control signal PWM300 is applied, the first current path controller S100 and the second current path controller S200 are turned off at a predetermined time t, and the third current path controller S300 is turned off. Is turned on. Thus, as shown in FIG. 3, the constant current path Ic provided by the constant current providing unit I100 is controlled by the first LED group G100, the second LED group G200, and the third current path control. It is formed along the portion (S300). That is, a constant current is provided to the first LED group G100 and the second LED group G200 so that the LEDs D101 to D103 and the second LED group G200 of the first LED group G100 are provided. The light emitting diodes D201 to D203 are turned on, but since the constant current is not provided to the light emitting diodes D301 to D303 of the third light emitting diode group G300, the light emitting diodes D201 to D203 are turned off.

Therefore, the driving device of the LED according to the embodiment of the present invention adjusts the current path of the constant current by using the current path control units (S100, S200, S300) for each LED group (G100, G200, G300). Thus, only one constant current providing unit I100 can be used.

Herein, the number n of the light emitting diodes D101 to D103, D201 to D203, and D301 to D303 of the light emitting diode groups G100, G200, and G300 is preferably 2 or more and 15 or less. When the number n of the light emitting diodes D101 to D103, D201 to D203, and D301 to D303 of the light emitting diode groups G100, G200, and G300 exceeds 15, the respective current path control units S100, It is not preferable because the voltage applied to S200 and S300 increases.

On the other hand, it is preferable to further include an overcurrent protection unit (I200) in the third current path control unit (S300). As a result, it is possible to suppress the overcurrent flowing through the current path control units S100, S200, and S300. The overcurrent protection unit I200 may be formed of a zener diode or a resistor.

Referring to FIG. 5, a driving apparatus of a light emitting diode according to another embodiment of the present invention will be described. 5 is a configuration diagram of a driving device of a light emitting diode according to another embodiment of the present invention.

As shown in FIG. 5, the driving apparatus of the LED according to another embodiment of the present invention includes the LED groups G110, G210, and G300, the constant current providing unit I1000, and the group activating units S110, S210, and S310. And a group activation signal providing unit P1000.

The light emitting diode groups G110, G210, and G310 have a plurality of light emitting diodes D111 to D113, D211 to D213, and D311 to D313 connected in series, and the light emitting diode groups G110, G210, and G310 are connected in series. ) Are connected in parallel to each other. The constant current providing unit I1000 provides a constant current to the LED groups G110, G210, and G310, and the group activators S110, S210, and S310 are connected in series to each of the LED groups G110, G210, and G310. Connected to activate each of the LED groups (S110, S210, S310).

The group activation signal providing unit P1000 provides group activation signals PWM110, PWM210, and PWM310 which are pulse signals to the group activation units S110, S210, and S310, respectively. The group activation signal providing unit P1000 may sequentially provide the group activation signals PWM110, PWM210, and PWM310 for a predetermined time. For example, when the driving device of the light emitting diode is driven at 60 Hz, the group activation signal providing unit P1000 sequentially processes the group activation signals PWM110, PWM210, and PWM310 during 1/60 sec (about 16.7 msec). Can be provided as

6 and 7 will be described in more detail with respect to the driving device of the light emitting diode according to another embodiment of the present invention. 6 is a circuit diagram illustrating a detailed configuration of the constant current providing unit of FIG. 5. 7 is a graph illustrating group activation signals of a driving device of a light emitting diode according to another embodiment of the present invention.

As shown in FIG. 6, the constant current providing unit I1000 includes a constant current controller I3000, a voltage step-down circuit, and a resistor R110. Here, the voltage step-down circuit is for stepping down the power supply voltage VDD to a predetermined voltage. As described above, a Buck type voltage step-down circuit is widely used. Specifically, the buck type voltage step-down circuit may be composed of a switching element (Q110), an inductor (L110), a capacitor (C110), etc., the switching element (Q110) as a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET) Alternatively, a bipolar junction transistor (BJT) may be used.

A zener diode Z110 is connected between the first node N111 and the second node N112, and an inductor L110 is connected between the second node N112 and the third node N113. The capacitor C110 is connected between the first node N111 and the third node N113. The constant current controller I3000 is connected between the fourth node N114 and the sixth node N116, and the switching element Q110 between the second node N112, the fourth node N114, and the fifth node N115. ) Is connected, and a resistor R110 is connected between the fifth node N115 and the sixth node N116. The first LED group G110 and the first group activator S110 are connected between the first node N111 and the third node N117, and the first LED group G110 and the first group activator are connected. The second LED group G210 and the second group activator S210 are connected in parallel to S110, and the third LED is emitted to the first LED group G110 and the first group activator S110. The diode group G310 and the third group activator S310 are also connected in parallel.

Here, the power supply voltage VDD is applied to the first node N111, the ground voltage GND is applied to the sixth node N116, and the switching element Q110 is a pulse provided by the constant current controller I3000. It is activated or deactivated by a signal. When the switching element Q110 is activated, electrical energy is accumulated in the inductor L110 and the capacitor C110. When the switching element Q110 is deactivated, energy stored in the inductor L110 and the capacitor C110 is stored. It is emitted to the light emitting diode groups G110, G210, and G310. In addition, the zener diode Z110 suppresses the overvoltage from being applied to the switching element Q110, the resistor R110 adjusts the amount of current flowing through the switching element Q110, and the constant current controller I3000 is a switching element ( The power supply voltage VDD is stepped down to a predetermined voltage by adjusting the duty ratio of the pulse signal or the frequency of the pulse signal provided to the Q110. For example, when the driving device of the light emitting diode is used as a backlight for the liquid crystal display device, the power supply voltage VDD is provided with 24 V, and the voltage is 6 V to 18 V using the Buck type voltage step-down circuit. Step down to the light emitting diode groups (G110, G210, G310).

On the other hand, the first group activator S110 is activated by the first group activation signal PWM110 and transmits a constant current provided by the constant current provider I1000 to the first LED group G110, thereby providing the first LED group. By activating (G110), the second group activation unit (S210) is activated by the second group activation signal (PWM210) to deliver a constant current provided by the constant current providing unit (I1000) to the second LED group (G210) The second LED group G210 is activated, and the third group activation unit S310 is activated by the third group activation signal PWM310, and the constant current providing unit I1000 is provided to the third LED group G310. The third LED group G310 is activated by transferring a constant current. The group activators S110, S210, and S310 may be formed of a metal oxide semiconductor field effect transistor (MOS FET) or a bipolar junction transistor (BJT).

As shown in FIG. 5, the group activators S110, S210, and S310 are configured as nMOS FETs, and as shown in FIG. 7, the first group activator S110 includes a first group enable signal. (PWM110) is applied, the second group activation unit (S210) is applied to the second group activation signal (PWM210), the third group activation unit (S310) is applied to the third group activation signal (PWM310), During the high state maintenance period of the activation signals (Ton1, Ton2, Ton3), the group activation parts are activated to activate the LED groups. That is, the activation time of each of the LED groups may be adjusted in proportion to the duty ratios Ton1 / T, Ton2 / T, and Ton3 / T of the group activation signals. As shown in FIG. 7, when the duty ratio Ton1 / T of the first group activation signal PWM1 is shortest and the duty ratio Ton3 / T of the third group activation signal PWM310 is longest, The activation time of the first LED group G110 is shortest and the activation time of the third LED group G310 is longest.

As a result, the luminance of each of the LED groups G110, G210, and G310 can be adjusted independently, and thus, when used as a backlight for a liquid crystal display, partial luminance can be adjusted.

Therefore, the driving apparatus of the LED according to another embodiment of the present invention uses the LED activation groups S110, S210, and S310 to the LED groups G110, G210, and G310, respectively. By controlling the activation time of each of the G310, the luminance of each of the LED groups G110, G210, and G310 may be independently controlled while using only one constant current providing unit I1000.

Here, the number k of light emitting diodes D111 to D113, D211 to D213, and D311 to D313 of the light emitting diode groups G110, G210, and G310 is preferably 2 or more and 15 or less. When the number k of the light emitting diodes D111 to D113, D211 to D213, and D311 to D313 of the light emitting diode groups G110, G210, and G310 exceeds 15, the respective group activation units S110, It is not preferable because the voltage applied to S210 and S310 increases.

Meanwhile, it is preferable to further include overcurrent protection units I110, I210, and I310 between each of the LED groups G110, G210, and G310 and each of the group activators S110, S210, and S310. As a result, it is possible to suppress the overcurrent from flowing through the group activators S110, S210, and S310. The overcurrent protection units I110, I210, and I310 may be formed of a zener diode or a resistor.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. I can understand that.

Therefore, the above-described embodiments will be described in detail so that the disclosure of the present invention may be completed, and those skilled in the art may easily implement the technical idea of the present invention. It is to be understood to be illustrative and not limitative in all respects, as it is provided to fully inform the person skilled in the art the scope of the invention, and the invention is defined only by the scope of the claims. .

The light emitting diode driving apparatus according to the embodiment of the present invention configured as described above uses a single constant current providing circuit to provide a plurality of light emitting diodes when used as a backlight of a flat panel display such as a liquid crystal display. By dividing the driving into a plurality of groups, the circuit configuration of the driving device of the light emitting diode can be simplified and the cost of the driving device of the light emitting diode can be reduced.

In addition, when the LED driving apparatus according to another embodiment of the present invention is used as a backlight of a flat panel type display device such as a liquid crystal display device, each of the LED groups uses group activators for each of the LED groups. By adjusting each activation time, the luminance of each of the LED groups may be independently controlled while using only one constant current providing unit.

Claims (13)

Light emitting diode groups in which a plurality (n) of light emitting diodes are connected in series; A constant current providing unit providing a constant current to the LED groups; Current path control units connected to each of the LED groups in parallel to adjust the current path of the constant current; And A current path control signal providing unit configured to provide current path control signals to each of the current path control units, The LED groups are connected in series, The constant current providing unit stores a switching device that is activated or deactivated by a pulse signal provided by a constant current controller, a resistor that adjusts the amount of current flowing through the switching device, and when the switching device is activated, accumulates electrical energy flowing through the switching device. And an inductor and a capacitor configured to emit the accumulated electrical energy to the light emitting diode groups when the switching element is inactivated. The method of claim 1, And a number n of light emitting diodes of the light emitting diode groups is 2 or more and 15 or less. The method of claim 1, The current path control unit includes a metal oxide semiconductor field effect transistor (MOS FET) or a bipolar junction transistor (BJT). 4. The method according to any one of claims 1 to 3, And an overcurrent protection unit configured to suppress an overcurrent from flowing through any one of the current path adjusting units. 5. The method of claim 4, The overcurrent protection unit is a drive device of a light emitting diode, characterized in that consisting of a Zener diode (Zener Diode) or a resistor. Light emitting diode groups in which a plurality (k) of light emitting diodes are connected in series; A constant current providing unit providing a constant current to the LED groups; Group activators connected in series to each of the LED groups to activate each of the LED groups; And A group activation signal providing unit providing group activation signals to each of the group activation units, The LED groups are connected in parallel, The constant current providing unit stores a switching element that is activated or deactivated by a pulse signal provided by a constant current controller, a resistor that adjusts the amount of current flowing through the switching element, and when the switching element is activated, accumulates electrical energy flowing through the switching element. And an inductor and a capacitor configured to emit the accumulated electrical energy to the light emitting diode groups when the switching element is inactivated. The method of claim 6, And a number k of light emitting diodes of the light emitting diode groups is 2 or more and 15 or less. The method of claim 6, The group activator may include a metal oxide semiconductor field effect transistor (MOS FET) or a bipolar junction transistor (BJT). The method of claim 6, The group activation signals are pulse signals, and the activation time of each of the LED groups is adjusted in proportion to the duty ratio of each of the group activation signals. The method according to any one of claims 6 to 9, And an overcurrent protection unit for suppressing an overcurrent flowing between each of the LED groups and each of the group activation units. The method of claim 10, The overcurrent protection unit is a drive device of a light emitting diode, characterized in that consisting of a Zener diode (Zener Diode) or a resistor. 7. The method according to claim 1 or 6, The constant current providing unit, And a Zener diode for suppressing the application of overvoltage to the switching element. 7. The method according to claim 1 or 6, The constant current control unit, And controlling the duty ratio of the pulse signal or the frequency of the pulse signal.

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