TWI420448B - Led backlight module, a driving method thereof, and a display thereof - Google Patents

Description

Light-emitting diode backlight module, driving method thereof and display device applied thereto

The present invention relates to a light-emitting diode backlight module, and more particularly to a diode backlight module capable of reducing the cost of a light-emitting diode component.

Manufacturers of light-emitting diodes (LEDs) classify the light-emitting diodes into different classification levels (Bin) depending on the electrical characteristics of the light-emitting diodes, such as wavelength, brightness, and turn-on voltage. The conventional diode backlight module uses the same classification level of the light-emitting diodes to make the display brightness of the backlight module uniform and obtain better circuit driving efficiency.

Figure 1 is a circuit diagram showing a conventional diode backlight module. Referring to FIG. 1 , the conventional diode backlight module 100 includes LED strings 110 , 120 , and 130 . All of the light-emitting diodes of the conventional diode backlight module 100 belong to the same classification level, and the threshold voltages of all the light-emitting diodes are approximate. The LED string 110 includes LEDs D11, D12 and D13 coupled in series, and the LED string 120 includes LEDs D21, D22 and D23 coupled in series, and the LED string 130 comprises a series connection. The coupled LEDs D31, D32 and D33. One end of the LED strings 110 to 130 is supplied with a power supply voltage Vled. Since the threshold voltages of all the LEDs of the diode backlight module 100 are similar, the voltages Vf1, Vf2 and Vf3 of the other ends of the LED strings 110 to 130 are similar. Therefore, the current flowing through the LED strings 110 to 130 is also approximate. In this way, the brightness of each diode is similar, so that the diode backlight module can provide both Evenly display brightness.

However, the conventional diode backlight module can only use the light-emitting diodes of the same classification level, which will increase the cost of component screening. If the LEDs of different classification levels are used, the display brightness of the conventional diode backlight module is not uniform, and the display quality is lowered. Therefore, how to provide a diode backlight module, which can simultaneously use different classification levels of light-emitting diodes to reduce cost and provide uniform display brightness, is an industry-oriented goal.

The invention relates to a light-emitting diode backlight module, which can simultaneously use different classification levels of light-emitting diodes while still providing uniform backlight.

According to a first aspect of the present invention, a backlight module of the present invention includes a first stage and a second stage LED circuit, a comparator, M switches and a switch controller. The first stage and second stage LED circuits respectively comprise M first LEDs and M second LEDs. The comparator compares the node voltage of the cathode of the first light-emitting diode and compares the turn-on voltage between the anode and the cathode when the second light-emitting diode is turned on to obtain a comparison result. The switch controller controls, according to the comparison result, that the cathode of the first light-emitting diode corresponding to one of the M switches is connected to the anode of one of the M second light-emitting diodes, wherein the first light emitting the highest node voltage The cathode of the diode is connected to the anode of the second light-emitting diode having the highest on-voltage, and the cathode of the first light-emitting diode that outputs the second highest node voltage is connected to the second having the second highest on-voltage The anode of the light-emitting diode, and the connection relationship between the cathode of the remaining first light-emitting diode and the anode of the second light-emitting diode, and the like. Where M is a positive integer greater than one.

According to a second aspect of the present invention, a display device includes a display panel and a light emitting diode backlight module. The LED backlight module comprises a first-level LED circuit, a second-stage LED circuit, a comparator, M first switches and a first switch controller. The first stage light emitting diode circuit includes M first light emitting diodes. The second stage light emitting diode circuit includes M second light emitting diodes. The comparator compares the node voltages of the cathodes of the M first light-emitting diodes, and compares the turn-on voltage between the anode and the cathode of the M second light-emitting diodes during the turn-on to obtain a comparison result. The first switch controller controls, according to the comparison result, that the cathode of the first light-emitting diode corresponding to one of the M first switches is connected to the anode of one of the M second light-emitting diodes, wherein the highest node is output The cathode of the first light-emitting diode of the voltage is connected to the anode of the second light-emitting diode having the highest turn-on voltage, and the cathode of the first light-emitting diode that outputs the voltage of the second highest node is connected to have the second highest conductivity The anode of the second light-emitting diode of the voltage, the connection relationship between the cathode of the remaining first light-emitting diode and the anode of the second light-emitting diode, and the like, so that the first and second light-emitting diodes provide backlight To the display panel. Where M is a positive integer greater than one.

According to a third aspect of the present invention, a driving method of a light emitting diode backlight module is provided for a light emitting diode backlight module. The LED backlight module includes a first-level LED circuit and a second-level LED circuit. The first and second stage LED circuits respectively include M first LEDs and M second LEDs. Drive method includes Column step. First, the node voltage of the cathode of the first light-emitting diode is compared, and the conduction voltage between the anode and the cathode when the second light-emitting diode is turned on is compared to obtain a comparison result. Thereafter, according to the comparison result, the cathode of the first light emitting diode that outputs the highest node voltage is connected to the anode of the second light emitting diode having the highest turn-on voltage, and the first light emitting diode of the second highest node voltage is output. The cathode is connected to the anode of the second light-emitting diode having the second highest turn-on voltage, and the connection relationship between the cathode of the remaining first light-emitting diode and the anode of the second light-emitting diode is similar. Where M is a positive integer greater than one.

In order to make the above-mentioned contents of the present invention more comprehensible, a preferred embodiment will be described below, and in conjunction with the drawings, a detailed description is as follows:

FIG. 2 is a circuit diagram of a backlight module of a light emitting diode according to an embodiment of the invention. In FIG. 2, the LED backlight module 200 includes a first-level LED circuit D1, a second-stage LED circuit D2, a comparator 210, and M first switches S1 (1). ) to S1 (M) and the first switch controller 220. Where M is a positive integer greater than one. The first stage light emitting diode circuit D1 includes M first light emitting diodes D1(1) to D1(M). The second stage light emitting diode circuit includes M second light emitting diodes D2(1) to D2(M).

The comparator 210 compares the node voltages of the cathodes of the first light-emitting diodes D1(1) to D1(M), and compares the second light-emitting diodes D2(1) to D2(M) between the anode and the cathode when conducting Turn-on voltage.

The first switch controller 220 is configured to control each of the first switches, each of which will The cathode of the first light-emitting diode corresponding to the first switch is connected to the anode of one of the M second light-emitting diodes D2(1) to D2(M). Wherein, the cathode of the first light-emitting diode that outputs the highest node voltage is connected to the anode of the second light-emitting diode having the highest on-voltage. The cathode of the first light-emitting diode that outputs the second highest node voltage is connected to the anode of the second light-emitting diode having the second highest turn-on voltage. The connection relationship between the cathode of the remaining first light-emitting diode and the anode of the second light-emitting diode is the same.

FIG. 3 is a circuit diagram of a backlight module of a light emitting diode according to another embodiment of the present invention. In FIG. 3, the LED backlight module 300 includes a first-stage LED circuit D1, a second-stage LED circuit D2, a third-stage LED circuit D3, and comparators 311 and 312. The switch controllers 321 and 322, the M first switches S1(1) to S1(M), and the M second switches S2(1) to S2(M) and the subtractor 330. The turn-on voltages of all the light-emitting diodes in the LED backlight module 300 are not equal.

The operation of the light-emitting diode backlight module 300 will be described. First, the LED backlight module 300 needs to obtain the second LEDs D2(1) to D2(M) and the third LEDs D3(1) to D3(M) between the anode and the cathode when conducting. Turn-on voltage.

The first light-emitting diodes D1(1) to D1(M) are supplied with a power supply voltage Vled, which respectively outputs node voltages Vn1(1) to Vn1(M). In the embodiment of the present invention, the switch controller 321 controls the first switch S1(j) to initially connect the cathode of the corresponding first light-emitting diode D1(j) to the M second light-emitting diodes D2 ( The anode of j) is such that the second light-emitting diode D2(j) is turned on. Thus, the cathodes of the second light-emitting diodes D2(1) to D2(M) respectively output the node voltages Vn2(1) to Vn2(M). its Where j is a positive integer less than M.

The subtractor 330 receives the node voltages Vn1(1) to Vn1(M) and the node voltages Vn2(1) to Vn2(M), and generates a difference between the node voltages Vn1(j) and Vn2(j). Since the cathode system of the first light-emitting diode D1(j) is initially connected to the anode of the second light-emitting diode D2(j), the node voltage of the anode of the second light-emitting diode D2(j) is equal to Vn1 (j). Therefore, the difference between the node voltages Vn1(j) and Vn2(j) is the turn-on voltage Vd2(j) of the second light-emitting diode D2(j).

Similarly, in the embodiment of the present invention, the switch controller 322 controls the second switch S2(j) to initially connect the second LED D2(j) to the third LED D3(j), respectively. . The subtractor 330 receives the node voltage Vn3(j) generated at the cathode after the third light-emitting diode D3(j) is turned on. Similarly, the subtractor 330 generates a difference between the node voltages Vn2(j) and Vn3(j), that is, the turn-on voltage Vd3(j) of the third light-emitting diode D3(j).

Thus, by initially connecting the cathodes of the M first light-emitting diodes to the anodes of one of the M second light-emitting diodes, respectively, the cathodes of the M second light-emitting diodes are respectively connected to the M first The anode of one of the three light-emitting diodes, the subtractor 330 obtains the turn-on voltages Vd2(1) to Vd2(M) of the M second light-emitting diodes, and the turn-on voltage Vd3 of the M third light-emitting diodes ( 1) to Vd3 (M).

Next, the comparator 311 compares the height relationship of the node voltages Vn1(1) to Vn1(M), and compares the relationship between the on-voltages Vd2(1) to Vd2(M) of the second light-emitting diodes. The comparator 311 outputs its comparison result to the switch controller 321.

The switch controller 321 controls the first switch according to the comparison result S1(1) to S1(M), reconnecting the cathodes of the first light-emitting diodes D1(1) to D1(M) to the second light-emitting diodes D2(1) to D2(M), respectively An anode. Wherein, the cathode of the first light-emitting diode that outputs the highest node voltage is connected to the anode of the second light-emitting diode having the highest on-voltage. The cathode of the first light-emitting diode that outputs the second highest node voltage is connected to the anode of the second light-emitting diode having the second highest turn-on voltage. The connection relationship between the cathode of the remaining first light-emitting diode and the anode of the second light-emitting diode is the same.

Similarly, after reconnecting the first light-emitting diodes D1(1) to D1(M) and the second light-emitting diodes D2(1) to D2(M), the second light-emitting diode D2(1) To D2 (M), a new node voltage Vn2'(1) to Vn2'(M) is output to the comparator 312 at the cathode after being turned on.

The comparator 312 compares the relationship between the high and low relationship of the node voltages Vn2'(1) to Vn2'(M) and the on-voltages Vd3(1) to Vd3(M) of the third light-emitting diode, and outputs the comparison result to the switch. Controller 322.

Similarly, the switch controller 322 controls the first switches S2(1) to S2(M) according to the above comparison result, respectively reconnecting the cathodes of the second LEDs D2(1) to D2(M) to the third An anode of one of the light-emitting diodes D3(1) to D3(M). The cathode system of the second light emitting diode that outputs the highest node voltage and the second highest node voltage is respectively connected to the anode of the third light emitting diode having the highest on voltage and the second highest on voltage. The connection relationship between the cathode of the remaining second light-emitting diode and the anode of the third light-emitting diode is the same.

An example of the effect of the LED backlight module of the embodiment of the present invention will be described. Figure 4A shows the light-emitting two when the initial connection of the light-emitting diode A partial circuit diagram of an example of the polar body backlight module 300. FIG. 4B is a partial circuit diagram showing an example of the LED backlight module 300 after reconnecting the LED. In this example, the M system is equal to 3. For convenience of description, FIG. 4 illustrates only the connection of each of the LEDs in the first, second and third LED circuits D1, D2 and D3 of the LED backlight module 300. relationship.

In this example, the cathodes of the first light-emitting diodes D1(1) to D1(3) are initially connected to the anodes of the second light-emitting diodes D2(1) to D2(3), respectively, and the second light-emitting The cathodes of the diodes D2(1) to D2(3) are initially connected to the anodes of the third light-emitting diodes D3(1) to D3(3), respectively. In this example, it is assumed that the power supply voltage Vled is 10V. And assuming that the first, second, and third-stage LED circuits are initially connected, the obtained node voltages Vn1(1) to Vn1(3) are equal to 9.3V, 9.4V, and 9.2V, respectively, and the node voltage Vn2 ( 1) to Vn2(3) are equal to 8.5V, 8.8V and 8.3V, respectively, and the node voltages Vn3(1) to Vn3(3) are equal to 7.8V, 8.1V and 7.5V, respectively.

The subtractor 330 obtains the turn-on voltages Vd2(1) to Vd2(3) of the second light-emitting diodes according to the node voltages, which are equal to 0.8V, 0.6V, and 0.9V, respectively, and obtains the turn-on voltage Vd3 of the third light-emitting diode. (1) to Vd3 (3) are equal to 0.7V, 0.7V and 0.8V, respectively. That is, the on-voltages of the light-emitting diodes in the first-stage, second-stage, and third-stage light-emitting diode circuits are not equal.

Next, the comparator 311 compares the high-low relationship of the node voltages Vn1(1) to Vn1(3), and compares the relationship between the on-voltages Vd2(1) to Vd2(3) of the second light-emitting diodes, and outputs the comparison result. To the switch controller 321.

The switch controller 321 will output the highest node voltage according to the comparison result. The cathode of the first light-emitting diode D1 (2) (i.e., 9.4 V) is connected to the anode of the second light-emitting diode D2 (3) having the highest on-voltage (i.e., 0.9 V) as shown in Fig. 4B. The switch controller 321 connects the cathode of the first light-emitting diode D1(1) that outputs the second highest node voltage (ie, 9.3V) to the second light-emitting diode D2 having the second highest turn-on voltage (ie, 0.8V) ( 1) The anode. In addition, the switch controller 321 connects the cathode of the first light-emitting diode D1 (3) that outputs the lowest node voltage (ie, 9.2 V) to the second light-emitting diode D2 having the lowest turn-on voltage (ie, 0.6 V) ( 2) The anode.

Thus, the cathodes of the second light-emitting diodes D2(1) to D2(3) respectively output new node voltages Vn2'(1) to Vn2'(3), which are equal to 8.5V, 8.6V and 8.5V, respectively.

After that, the comparator 312 compares the high-low relationship of the node voltages Vn2'(1) to Vn2'(3), and compares the high-low relationship of the on-voltages Vd3(1) to Vd3(3) of the third light-emitting diode, and The comparison result is output to the switch controller 322.

Similarly, the switch controller 322 connects the cathode of the second light-emitting diode D2(2) outputting the highest node voltage (ie, 8.6V) to the third light having the highest turn-on voltage (ie, 0.8V) according to the comparison result. The anode of diode D3 (3) is shown in Figure 4B. The switch controller 322 connects the cathodes of the first light-emitting diodes D2(1) and D2(3) that output the second-highest node voltage (ie, 8.5V) to the third having the second highest turn-on voltage (ie, 0.7V) The anodes of the light-emitting diodes D3(1) and D3(2).

Thus, the cathodes of the third light-emitting diodes D3(1) to D3(3) output new node voltages Vn3'(1) to Vn3'(3), respectively, which are equal to 7.8V.

The light-emitting diodes in the conventional light-emitting diode backlight module are connected in the same manner as the light-emitting diodes in the backlight module of the embodiment of the present invention. In Fig. 4A, the cathodes of the first light-emitting diodes D1(1) to D1(3) are initially directly connected to the anodes of the second light-emitting diodes D2(1) to D2(3), respectively, and the second light-emitting The cathodes of the diodes D2(1) to D2(3) are initially directly connected to the anodes of the third light-emitting diodes D3(1) to D3(3), respectively. Thus, the cathodes of the third light-emitting diodes initially output node voltages Vn3(1) to Vn3(3), respectively, which are equal to 7.8V, 8.1V, and 7.4V. The node voltages Vn3(1) to Vn3(3) are not close to each other. Therefore, the current flowing through the series of light-emitting diodes D1(1), D2(1), and D3(1) flows through the series-connected light-emitting diodes D1(2), D2(2), and D3(2). The current, and the current system flowing through the series connected LEDs D1 (3), D2 (3) and D3 (3) are very different. Therefore, the brightness of the three sets of light-emitting diodes connected in series is not equal.

In Fig. 4B, the node voltages Vn2'(1) to Vn2'(3) of the cathodes of the reconnected second light-emitting diodes are equal to 8.5V, 8.6V and 8.5V, respectively. Compared with FIG. 4A, the node voltages Vn2(1) to Vn2(3) of the cathode of the second light-emitting diode are initially equal to 8.5V, 8.8V and 8.3V, respectively, and the nodes after reconnection in FIG. 4B The voltages Vn2'(1) to Vn2'(3) are close to each other. In other words, after reconnecting the first and second light emitting diodes, the sum of the turn-on voltages of the three sets of interconnected first and second light emitting diodes are close to each other.

Similarly, the node voltages Vn3'(1) to Vn3'(3) of the cathodes of the reconnected third light-emitting diodes are all equal to 7.8V. Compared with the fourth embodiment, the node voltages Vn3(1) to Vn3(3) of the cathode of the second light-emitting diode are initially compared. The node voltages Vn3'(1) to Vn3'(3) after reconnection in Fig. 4B are preferably equal to each other, respectively, equal to 7.8V, 8.1V, and 7.4V. In other words, after reconnecting the second and third light emitting diodes, the sum of the turn-on voltages of the three sets of interconnected first, second and third light emitting diodes are equal to each other.

Therefore, in FIG. 4A, the current flowing through the series of light-emitting diodes D1(1), D2(1), and D3(1) flows through the series-connected light-emitting diodes D1(2) and D2(3). The current with D3 (2) is substantially equal to the current flowing through the series of light-emitting diodes D1 (3), D2 (2), and D3 (3). Therefore, the brightness of the three sets of light-emitting diodes connected in series is substantially equal. As such, the LED backlight module of the embodiment of the present invention can provide a backlight with uniform brightness.

FIG. 5 is a flow chart showing the driving manner of the LED backlight module according to the embodiment of the present invention. The driving method of this embodiment includes the following steps. First, as in step (a), the first and second stage LED circuits D1 and D2 are turned on. Next, as step (b), comparing the node voltages of the cathodes when the first light-emitting diodes D1(1)-D1(M) are turned on, and comparing the second light-emitting diodes D2(1)-D2(M) The turn-on voltage between the anode and the cathode during conduction. Then, as in step (c), the cathodes of the respective first light-emitting diodes D1(1)-D1(M) are connected to the anodes of the corresponding second light-emitting diodes D2(1)-D2(M).

In this example, initially, the first, second, and third light-emitting diodes D1(1), D2(1), and D3(1) are connected, and the first, second, and third light-emitting diodes are connected. The polar bodies D1(2), D2(2) and D3(2) are connected to the first, second and third light-emitting diodes D1(3), D2(3) and D3(3) as an example to obtain The turn-on voltage of each of the second and third light emitting diodes. Practical application In the initial stage, each of the first, second, and third light emitting diodes may be connected in different connection manners, and the ON voltages of the respective second and third light emitting diodes are correspondingly obtained.

In this example, the action and effect of the LED backlight module of the embodiment of the present invention are described by taking M equal to 3. In practice, however, M can be any positive integer greater than one.

In the embodiment of the present invention, the three-level LED circuits D1, D2, and D3 are taken as an example. In practical applications, the LED backlight module of the embodiment of the present invention may include more LED dipole circuits. Each of the light-emitting diodes in the adjacent two-stage LED circuit after the third-stage LED circuit obtains its turn-on voltage in the above initial manner, and reconnects the second and third-level lights with the above-mentioned The way of the diode circuit is to reconnect.

FIG. 6 is a block diagram of a display device according to an embodiment of the present invention. Referring to FIG. 6, the display device 500 includes a display panel 510 and a light-emitting diode backlight module 200 according to an embodiment of the present invention. The LED backlight module 200 provides a backlight Lb to the display panel 510. Since the backlight Lb provided by the LED backlight module 200 is uniform, the display panel 510 can provide excellent development quality.

Therefore, the LED backlight module of the embodiment of the present invention reconnects each other according to the order of the node voltages outputted by the cathodes of the first LEDs and the conduction voltage of the second LEDs. The first light emitting diode and each of the second light emitting diodes. In this way, the node voltages outputted by the cathodes of the reconnected second light-emitting diodes can be made close. In the same way, connecting the LED circuits of the various levels in the same way can make The cathodes of the respective light-emitting diodes of the last-stage LED circuit have similar node voltages, and further the currents flowing through the LEDs of each group are similar.

Therefore, even if the on-voltage of the light-emitting diodes in the LED backlight module is not equal, the LED backlight module can provide a uniform backlight. Therefore, the LED backlight module of the embodiment of the invention can simultaneously use the LEDs of different classification levels to reduce the cost of component screening and can simultaneously achieve the image quality.

In view of the above, the present invention has been disclosed in a preferred embodiment, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

110, 120, 130‧‧‧Lighting diode strings

D1‧‧‧first-level LED circuit

D2‧‧‧second-level LED circuit

D3‧‧‧ third-level LED circuit

D11, D12, D13, D1(1), D1(2), D1(3), D1(M), D2(1), D2(2), D2(3), D2(M), D3(1) , D3(2), D3(3), D3(M)‧‧‧Lighting diodes

S1(1), S1(2), S1(M)‧‧‧ first switch

S2 (1), S2 (2), S2 (M) ‧ ‧ second switch

210, 311, 312‧‧‧ comparator

321, 322‧‧‧ switch controller

330‧‧‧Subtractor

510‧‧‧ display panel

Figure 1 is a circuit diagram showing a conventional diode backlight module.

FIG. 2 is a circuit diagram of a backlight module of a light emitting diode according to an embodiment of the invention.

FIG. 3 is a circuit diagram of a backlight module of a light emitting diode according to another embodiment of the present invention.

FIG. 4A is a partial circuit diagram showing an example of a light-emitting diode backlight module when the light-emitting diode is initially connected.

FIG. 4B is a partial circuit diagram showing an example of a light-emitting diode backlight module after the light-emitting diode is reconnected.

FIG. 5 is a flow chart showing a driving method of the LED backlight module according to the embodiment of the present invention.

FIG. 6 is a block diagram of a display device according to an embodiment of the present invention.

D1‧‧‧first-level LED circuit

D2‧‧‧second-level LED circuit

D3‧‧‧ third-level LED circuit

D1(1), D1(2), D1(M), D2(1), D2(2), D2(M), D3(1), D3(2), D3(M)‧‧‧Lighting pole body

S1(1), S1(2), S1(M)‧‧‧ first switch

S2 (1), S2 (2), S2 (M) ‧ ‧ second switch

311, 312‧‧‧ comparator

321, 322‧‧‧ switch controller

330‧‧‧Subtractor

Claims (14)

A light-emitting diode backlight module includes: a first-level LED circuit comprising M first LEDs; and a second-level LED circuit comprising M second LEDs Comparing a node, comparing a node voltage of the cathodes of the M first light-emitting diodes during turn-on, and comparing a turn-on voltage between the anode and the cathode when the two second light-emitting diodes are turned on, to obtain a comparison result; M first switches; and a first switch controller, according to the comparison result, controlling a cathode of the first light-emitting diode corresponding to one of the M first switches to be connected to the M An anode of one of the second light-emitting diodes, wherein the cathode of the first light-emitting diode that outputs the highest node voltage is connected to the anode of the second light-emitting diode having the highest turn-on voltage, and outputs the second highest node The cathode of the first light-emitting diode of the voltage is connected to the anode of the second light-emitting diode having the second highest turn-on voltage, and the connection of the cathode of the remaining first light-emitting diode to the anode of the second light-emitting diode Relationship and so on; among them, M A positive integer greater than one. The LED backlight module of claim 1, further comprising: a third-level LED circuit comprising M third LEDs; M second switches; Two switch controllers; The comparison circuit compares the node voltages of the cathodes of the M second light-emitting diodes during the turn-on, and compares the turn-on voltages between the anodes and the cathodes when the M third light-emitting diodes are turned on. According to another comparison result, the second switch controller controls, according to the another comparison result, a cathode of the second light emitting diode corresponding to one of the M second switches to be connected to the M third light emitting An anode of one of the diodes, wherein a cathode of the second light-emitting diode that outputs the highest node voltage is connected to the anode of the third light-emitting diode having the highest turn-on voltage, and outputs a second voltage of the second highest node voltage The cathode of the light-emitting diode is connected to the anode of the third light-emitting diode having the second highest turn-on voltage, and the connection relationship between the cathode of the remaining second light-emitting diode and the anode of the third light-emitting diode and so on . The light-emitting diode backlight module of claim 2, wherein the comparison circuit further comprises: a first comparator for comparing cathode nodes of the M first light-emitting diodes during conduction; Voltage, and comparing the turn-on voltage between the anode and the cathode when the M second light-emitting diodes are turned on; and a second comparator for comparing the cathodes of the M second light-emitting diodes during turn-on The node voltage is compared, and the conduction voltage between the anode and the cathode when the M third LEDs are turned on is compared. The light-emitting diode backlight module of claim 1, wherein the first switch controller initially controls each of the first switches, and one of the M first light-emitting diodes The cathode is connected to the anodes of the one of the two second light-emitting diodes to turn on the M second light-emitting diodes. The light-emitting diode backlight module further includes: a subtractor for generating Each of the second light-emitting diodes after being turned on The difference between the node voltage of the anode and the node voltage of the cathode is used as the turn-on voltage of each of the second light-emitting diodes. The illuminating diode backlight module of claim 1, wherein all of the illuminating diode systems of the illuminating diode backlight module belong to at least two classification levels (Bin). A display device includes: a display panel; and a light-emitting diode backlight module, comprising: a first-level light-emitting diode circuit, including M first light-emitting diodes; and a second-level light-emitting diode The circuit includes M second light-emitting diodes; a comparison circuit compares the node voltages of the cathodes of the M first light-emitting diodes during turn-on, and compares the M second light-emitting diodes during turn-on a turn-on voltage between the anode and the cathode to obtain a comparison result; M first switches; and a first switch controller, according to the comparison result, controlling the first one of the M first switches a cathode of the light emitting diode is connected to the anode of one of the M second light emitting diodes, wherein a cathode system of the first light emitting diode that outputs the highest node voltage is connected to the second having the highest turn-on voltage The anode of the light-emitting diode, the cathode of the first light-emitting diode that outputs the voltage of the second highest node is connected to the anode of the second light-emitting diode having the second highest turn-on voltage, and the cathode of the remaining first light-emitting diode And the second light emitting diode The connection relationship of the anodes is the same, so that the M first and the M second light emitting diodes provide backlight to The display panel; wherein M is a positive integer greater than one. The display device of claim 6, wherein the LED backlight module further comprises: a third-level LED circuit comprising M third LEDs; M second switches And a second switch controller; wherein the comparison circuit compares the node voltages of the cathodes of the M second light-emitting diodes during turn-on, and compares the anodes of the M third light-emitting diodes during turn-on And a turn-on voltage between the cathode and the cathode to obtain another comparison result, the second switch controller controls the cathode of the second light-emitting diode corresponding to one of the M second switches according to the another comparison result An anode connected to one of the M third light-emitting diodes, wherein a cathode of the second light-emitting diode that outputs the highest node voltage is connected to an anode of the third light-emitting diode having the highest turn-on voltage a cathode of a second light-emitting diode that outputs a second-high junction voltage is connected to an anode of a third light-emitting diode having a second highest turn-on voltage, and a cathode of the remaining second light-emitting diode and a third light-emitting diode Connection relationship of the anode of the body So on and so forth. The display device of claim 7, wherein the comparison circuit further comprises: a first comparator for comparing a node voltage of the cathodes of the M first light-emitting diodes during turn-on, and comparing the a turn-on voltage between the anode and the cathode when the M second light-emitting diodes are turned on; and a second comparator for comparing the turns of the M second light-emitting diodes The node voltage of the cathode is compared, and the conduction voltage between the anode and the cathode when the M third LEDs are turned on is compared. The display device of claim 6, wherein the first switch controller initially controls each of the first switches, and connects the cathodes of one of the M first light-emitting diodes to the An anode of one of the two second light-emitting diodes, wherein the two second light-emitting diodes are turned on, the light-emitting diode backlight module further includes: a subtractor for generating each of the turned-on The difference between the node voltage of the anode of the second light-emitting diode and the node voltage of the cathode is used as the turn-on voltage of each of the second light-emitting diodes. The display device of claim 6, wherein all of the light emitting diode systems of the light emitting diode backlight module belong to at least two classification levels (Bin). A driving method of a light-emitting diode backlight module for a light-emitting diode backlight module, the light-emitting diode backlight module comprising a first-level LED circuit and a second-level LED The first and second stage LED circuits respectively comprise M first LEDs and M second LEDs, the driving method comprising: comparing the M first LEDs a node voltage of the cathode when the body is turned on, and comparing the conduction voltage between the anode and the cathode when the M second light-emitting diodes are turned on to obtain a comparison result; and according to the comparison result, the highest node voltage is output The cathode of the first light emitting diode is connected to the anode of the second light emitting diode having the highest turn-on voltage, and the cathode of the first light emitting diode that outputs the second highest node voltage is connected to the second having the second highest turn-on voltage The anode of the light-emitting diode, the rest The connection relationship between the cathode of the first light-emitting diode and the anode of the second light-emitting diode is the same; wherein M is a positive integer greater than one. The driving method of claim 11, wherein the LED backlight module further comprises a third-level LED circuit, and the third-level LED circuit comprises M third illuminations. After the step of connecting the M first light emitting diodes and the M second light emitting diodes according to the comparison result, the driving method further comprises: comparing the M second light emitting two a node voltage of a cathode of the polar body, and comparing a turn-on voltage between the anode and the cathode when the M third light-emitting diodes are turned on to obtain another comparison result; and according to the other comparison result, the output is highest a cathode of the second light-emitting diode of the node voltage is connected to the anode of the third light-emitting diode having the highest turn-on voltage, and a cathode of the second light-emitting diode that outputs the second-high node voltage is connected to the cathode having the second highest turn-on voltage The anode of the third light-emitting diode, the connection relationship between the cathode of the remaining second light-emitting diode and the anode of the third light-emitting diode, and the like. The driving method of claim 12, wherein before the comparing the turn-on voltages of the M second and the M third light-emitting diodes, the driving method further comprises: initializing the a cathode of one of the M first light-emitting diodes is connected to an anode of one of the M second light-emitting diodes, and a cathode of one of the M second light-emitting diodes is connected to the M An anode of one of the third light emitting diodes such that each of the second light emitting diodes is electrically connected to each of the third light emitting diodes; a difference between a node voltage of the anode of each of the second light-emitting diodes and a node voltage of the cathode is generated as a turn-on voltage of each of the second light-emitting diodes, and each of the third light-emitting diodes is turned on after being turned on. The difference between the node voltage of the anode of the polar body and the node voltage of the cathode is used as the turn-on voltage of each of the third light-emitting diodes. The driving method of claim 11, wherein before the comparing the turn-on voltages of the M second light-emitting diodes, the driving method further comprises: initially, the M first light-emitting diodes a cathode of one of the bodies is connected to the anodes of one of the M second light-emitting diodes to turn on each of the second light-emitting diodes; and an anode of each of the second light-emitting diodes is turned on after the turn-on The difference between the node voltage and the node voltage of the cathode is used as the turn-on voltage of each of the second light-emitting diodes.