TWI467548B - Backlight module and driving method thereof - Google Patents

Description

Backlight module and driving circuit and driving method thereof

The present invention relates to a driving circuit for driving a light emitting diode, and more particularly to a driving circuit for a light emitting diode that utilizes a digitally programmable technology to save energy.

Please refer to FIG. 1 , which is a schematic diagram of a conventional backlight module. In order to ensure that each string of LED strings can work normally, the conventional backlight module 100 receives the feedback voltage of each string of LED strings through the controller to adjust the duty ratio of the pulse modulation signal. (duty ratio), and further adjust the driving voltage for driving each of the LED strings. Since the luminance of the light-emitting diode is proportional to the current flowing through it, in order to make the luminance of each string of the light-emitting diodes similar, a linear regulator architecture is used to achieve constant current control.

However, because of the component characteristics or process relationships of the light-emitting diodes, the forward voltage of each of the light-emitting diodes is different, and thus the turn-on voltage of each string of light-emitting diode strings is also different. Therefore, the controller must generate sufficient pulse width signal duty ratio to generate a sufficiently large driving voltage to ensure that each string of LED strings can work properly. At this time, the linear regulator as a fixed current control will cross the excess voltage across the drain and source of the transistor, and this crossover may cause power loss, efficiency degradation, and transistor overheating. problem.

Embodiments of the present invention provide a backlight module, and the backlight module includes a light emitting Unit, linear regulator and drive control unit. The light emitting unit outputs a feedback voltage and a reference current. The linear regulator is electrically connected to the light emitting unit and the linear regulator is used to receive and stabilize the reference current. The driving control unit is electrically connected to the lighting unit and the driving control unit receives and outputs a reference control signal to the linear regulator according to the feedback voltage. The linear regulator adjusts the voltage difference between the feedback voltage and the reference tracking voltage according to the reference control signal, wherein the reference tracking voltage is the reference reference voltage in the linear regulator plus the reference output voltage.

The embodiment of the invention further provides a driving circuit for driving the light emitting diode, the light emitting diode outputting the feedback voltage and the reference current, and the driving circuit comprises a linear regulator and a driving control unit.

The embodiment of the invention further provides a driving method, the steps of which include the following. Outputting a reference control signal according to the feedback voltage; and adjusting a voltage difference between the feedback voltage and the reference tracking voltage according to the reference control signal.

In summary, the backlight module and the driving circuit and the driving method thereof according to the embodiments of the present invention can not only recover the reference current output by the light emitting unit, but also provide the use to other circuit blocks or components, and the disclosure is disclosed. The linear regulator in the content can reduce the voltage difference between the feedback voltage and the reference tracking voltage by referring to the output voltage, thereby reducing the power consumption of the linear regulator, thereby achieving the power saving effect. .

The detailed description of the present invention and the accompanying drawings are to be understood by the claims The scope is subject to any restrictions.

Various illustrative embodiments are described more fully hereinafter with reference to the accompanying drawings. However, the inventive concept may be embodied in many different forms and should not be construed as being limited to the illustrative embodiments set forth herein. Rather, these exemplary embodiments are provided so that this invention will be in the In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Similar numbers always indicate similar components.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, such elements are not limited by the terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the inventive concept. As used herein, the term "and/or" includes any of the associated listed items and all combinations of one or more.

The present invention discloses a driving circuit for driving a light emitting diode. The driving circuit for driving the light emitting diode includes a linear regulator, a driving control unit, a voltage stabilizing unit and a dimming unit. Further, the driving circuit can be used to drive a backlight module or a lighting device, wherein the lighting device such as a street light, a traffic light or an advertising light is not limited to the enumerator.

For convenience of description and understanding of the disclosure, the following description will use a backlight module as an exemplary embodiment, but the disclosure is not limited to the backlight module. Those of ordinary skill in the art should be able to analogize to lighting devices such as street lights, traffic lights or advertising lights.

[Embodiment of Backlight Module]

Please refer to FIG. 2. FIG. 2 is a schematic diagram of a backlight module according to an embodiment of the invention. In this embodiment, the backlight module includes a light emitting unit 210 and a linear tone. The controller 220, the drive control unit 230, the voltage stabilization unit 240, and the dimming unit 250.

The light emitting unit 210 is electrically connected to the driving control unit 230. The dimming unit 250 is electrically connected between the driving control unit 230 and the lighting unit 210. The linear regulator 220 is electrically connected to the light emitting unit 210. The voltage stabilizing unit 240 is electrically connected to the driving control unit 230 and the linear regulator 220.

The light emitting unit 210 outputs at least one feedback voltage RVD to the driving control unit 230, and outputs at least one reference current RI to the linear regulator 220. In this embodiment, the light emitting unit 210 may be an array of light emitting diodes or an array of self-luminous elements.

The linear regulator 220 is configured to receive and stabilize the reference current RI to maintain the uniformity of illumination of the light emitting unit 210, wherein the linear regulator 220 is selectively connected to the reference output voltage ROV or the ground voltage GND according to the reference control signal RCS. Moreover, when the linear regulator 220 selects the reference output voltage ROV, the linear regulator 220 adjusts the voltage difference between the feedback voltage RVD and the at least one reference tracking voltage RVS by electrically connecting to the reference output voltage ROV, wherein the reference follows The voltage RVS is a reference reference voltage in the linear regulator 220 plus a reference output voltage ROV.

The drive control unit 230 receives and outputs at least one reference control signal RCS to the linear regulator 220 according to the feedback voltage RVD. The driving control unit 230 receives the input voltage VIN and converts the received input voltage VIN into a reference output voltage ROV. In the embodiment, the driving control unit 230 steps down the input voltage VIN to a reference output voltage ROV.

The voltage stabilizing unit 240 is configured to stabilize the reference output voltage ROV output by the driving control unit 230, wherein the output node of the reference output voltage ROV is between the voltage stabilizing unit 240 and the driving control unit 230. And, in this implementation The output node of the reference output voltage ROV can be electrically connected to other circuit blocks (not shown in FIG. 2) or components (not shown in FIG. 2) for use of the reference output voltage ROV.

The dimming unit 250 receives the input voltage VIN and the dimming control signal DCS, and outputs the dimming driving voltage VLED to the light emitting unit 210 according to the dimming control signal DCS. What will be further explained next is the operation of the backlight module 200.

Referring to FIG. 2, when the driving control unit 230 transmits the dimming control signal DCS to the dimming unit 250, the dimming unit 250 outputs a corresponding dimming driving voltage VLED according to the dimming control signal DCS to drive the light emitting unit 210. Then, the light emitting unit 210 generates a corresponding reference current RI and a feedback voltage RVD according to the received dimming driving voltage VLED, and transmits the same to the driving control unit 230 and the linear regulator 220, respectively. It is to be noted that if the dimming driving voltage VLED is too small to completely drive a part of the light emitting unit 210, no reference current RI is generated. Next, the drive control unit 230 determines whether the light emitting unit 210 has been completely driven according to the received feedback voltage RVD, that is, determines whether the light emitting unit 210 has all been lit. If the light emitting unit 210 is not fully illuminated, the driving control unit 230 adjusts the dimming control signal DCS according to the feedback voltage RVD, thereby increasing the dimming driving voltage VLED to drive the light emitting unit 210. The driving control unit 230 of this embodiment continuously corrects the dimming control signal DCS by using the feedback mechanism until the lighting unit 210 is completely lit.

Next, the backlight module 200 activates an energy saving mechanism. The driving control unit 230 converts the received input voltage VIN into a reference output voltage ROV, and stabilizes the reference output voltage by the voltage stabilizing unit 240. ROV. In other words, the reference output voltage ROV stabilized by the voltage stabilizing unit 240 is provided by the current supplied by the input voltage VIN (or the supplied energy). In this embodiment, after the light-emitting unit 210 is completely lit, when the linear regulator 220 is selectively electrically connected to the reference output voltage ROV according to the reference control signal RCS, the reference current RI flows to the linear regulator 220. Other circuit blocks or components, according to which the reference current RI is recovered to achieve energy saving effect, and the linear regulator 220 reduces the voltage difference between the feedback voltage RVD and the reference tracking voltage RVS by referring to the output voltage ROV. On the other hand, when the linear regulator 220 is selectively connected to the ground voltage GND according to the reference control signal RCS, it means that no action of recovering the reference current RI is made.

Further, the driving control unit 230 correspondingly outputs the reference control signal RCS to the linear regulator 220 according to the magnitude of the feedback voltage RVD to further adjust the reference tracking voltage RVS in the linear regulator 220, and enable the reference tracking voltage RVS. Try to approach the feedback voltage RVD as much as possible. In other words, the linear regulator 220 reduces the voltage difference between the feedback voltage RVD and the reference tracking voltage RVS according to the reference control signal RCS, wherein the reference tracking voltage RVS is the reference reference voltage in the linear regulator 220 plus the reference output. Voltage ROV. In the present embodiment, it is to be noted that in the process of adjusting the reference tracking voltage RVS, the occurrence of the reference tracking voltage RVS being greater than the feedback voltage RVD should be avoided.

Incidentally, in another embodiment, the designer can activate the energy saving mechanism of the backlight module 200 to recover the current before the lighting unit 210 is completely illuminated according to the circuit design requirement or the actual application requirement. action.

Therefore, compared to the reference current RI that is wasted under the prior art (ie, Directly flowing into the ground voltage GND), the disclosure can not only recover the reference current RI output by the light emitting unit 210 for use in other circuit blocks or components, and the linear regulator 220 in the present disclosure can be referenced by reference. The output voltage ROV is used to reduce the voltage difference between the feedback voltage RVD and the reference tracking voltage RVS to reduce the power consumption of the linear regulator 220, thereby achieving the power saving effect.

In order to explain the operation flow of the backlight module of the present invention in more detail, at least one of the following embodiments will be further described.

Before the following description is made, it should be noted that in the following various embodiments, portions different from the above-described embodiment of Fig. 2 will be described, and the remaining omitted portions are the same as those of the above-described embodiment of Fig. 2. In addition, for the sake of convenience, like reference numerals or numerals indicate similar elements.

[Another embodiment of the backlight module]

Please refer to FIG. 3. FIG. 3 is a schematic diagram of a detail of a backlight module according to an embodiment of the invention. The light emitting unit 210 in the present embodiment includes at least one light emitting diode string DS, wherein the light emitting diode string DS is connected in series by at least one light emitting diode. to make. The linear regulator 220 includes at least one first N-type transistor Mn1, at least one amplifier OP, at least one resistor R, and at least one demultiplexer 222. The drive control unit 230 includes a light-emitting diode drive controller 231, an analog-to-digital circuit 232, a step-down circuit 233, an analog-to-digital circuit 234, and a microcontroller 235. The voltage stabilizing unit 240 includes at least one storage capacitor SC. The dimming unit 250 includes an inductor L1, a second N-type transistor Mn2, a diode D1, and a dimming capacitor DC.

The output end of the LED array DS outputs the feedback voltage RVD to the drain of the corresponding first N-type transistor Mn1, and the LED driver controller 231 Analogous to digital circuit 232. The input end of the LED string DS receives the dimming driving voltage VLED, wherein the output terminal of the LED string DS outputs a reference current RI. The drain of the first N-type transistor Mn1 receives the feedback voltage RVD and the reference current RI, and the source of the first N-type transistor Mn1 outputs a reference tracking voltage RVS. The positive input terminal and the negative input terminal of the amplifier OP respectively receive the reference reference voltage VREF and the reference follow-up voltage RVS, and the output end of the amplifier OP is electrically connected to the gate of the first N-type transistor Mn1. One end of the resistor R receives the reference tracking voltage RVS, and the other end of the resistor R outputs the reference current RI. The demultiplexer 222 is electrically connected to the negative terminal of the reference reference voltage VREF and the other end of the resistor R, wherein the demultiplexer 222 can be implemented using at least one switch. One end of the storage capacitor SC is electrically connected to the reference output voltage VREF and the demultiplexer 222, and the other end of the storage capacitor SC is electrically connected to the ground voltage GND.

One end of the inductor L1 receives the input voltage VIN. The second N-type transistor Mn2 is electrically connected to the other end of the inductor L1, the source of the second N-type transistor Mn2 is electrically connected to the ground voltage GND, and the gate of the second N-type transistor Mn2 is received and dimmed. Signal DCS. The anode of the diode D1 is electrically connected to the other end of the inductor L1, and the cathode of the diode D1 outputs the dimming driving voltage VLED. One end of the dimming capacitor DC is electrically connected to the cathode of the diode D1, and the other end of the dimming capacitor DC is electrically connected to the ground voltage GND.

The LED driver controller 231 receives the feedback voltage RVD and outputs a dimming control signal DCS according to the feedback voltage RVD.

The analog-to-digital circuit 232 receives the feedback voltage RVD and converts the feedback voltage RVD into a digital signal DIS1.

The buck circuit 233 receives the input voltage VIN and steps down the input voltage VIN to the reference output voltage ROV and transmits it to the voltage stabilizing unit 240. in In this embodiment, the step-down circuit 233 can be a low drop out regulator or a direct current to direct current (DC-to-DC) circuit.

The analog-to-digital circuit 234 is electrically coupled to the buck circuit 233. The analog-to-digital circuit 234 receives the analog signal AIS and converts the analog signal AIS into a digital signal DIS2.

The microcontroller 235 is electrically coupled between the analog-to-digital circuit 232 and the analog-to-digital circuit 234. The microcontroller 235 receives the digital signals DIS1 and DIS2, and outputs a reference control signal RCS to the demultiplexer 222 based on the information carried by the digital signals DIS1 and DIS2. In an embodiment, the microcontroller 235 is further electrically connected to the LED driver controller 231, so that the designer can design the backlight module 300 not to activate the energy saving mechanism when the dimming is too dark. action.

What will be further explained next is the operation of the backlight module 300.

Referring to FIG. 3, when the LED driving controller 231 transmits the dimming control signal DCS to the second N-type transistor Mn2, the second N crystal Mn2 is turned on or off according to the dimming control signal DCS. Further, the size of the dimming driving voltage VLED is determined according to the length of the opening time of the second N-type transistor Mn2, that is, the dimming control signal DCS is determined by Pulse Width Modulation (PWM). The size of the light drive voltage VLED drives the LED string DS. Then, the LED string DS generates a corresponding reference current RI and a feedback voltage RVD according to the received dimming driving voltage VLED, and respectively transmits the feedback voltage RVD to the LED driver controller. 231. An analog-to-digital circuit 232 and a drain of the first N-type transistor Mn1. It is worth noting that if the drive voltage VLED is too small to drive at all When the LED string DS is illuminated, no reference current RI is generated.

Next, the LED driver controller 231 determines whether the LED string DS has been completely driven according to the received feedback voltage RVD, that is, determines whether the LED string DS has all been clicked. bright. If the LED string DS is not fully illuminated, the LED driver controller 231 adjusts the dimming control signal DCS according to the feedback voltage RVD, that is, increases the duty ratio of the pulse width modulation signal (duty Ratio), thereby increasing the dimming driving voltage VLED to drive the LED string DS. The LED driver controller 231 of the embodiment continuously corrects the duty ratio of the pulse width modulation signal by using the feedback mechanism until the LED string DS is fully turned on or completely lit.

Next, the backlight module 300 activates an energy saving mechanism. The step-down circuit 233 steps down the received input voltage VIN to the reference output voltage ROV, and stabilizes the reference output voltage ROV by the storage capacitor SC in the voltage stabilizing unit. In other words, the reference output voltage ROV stabilized by the storage capacitor SC is provided by the current supplied by the input voltage VIN (or the supplied energy). In this embodiment, after the LED string DS is completely lit, when the demultiplexer 222 is selectively connected to the reference output voltage ROV according to the reference control signal RCS, the reference current RI will be solved by the solution. The device 222 flows to other circuit blocks or components, thereby recovering the reference current RI to achieve energy saving. On the other hand, when the demultiplexer 222 is selectively connected to the ground voltage GND according to the reference control signal RCS, it means that no action of recovering the reference current RI is performed.

Further, the LED driver controller 231 correspondingly outputs the reference control signal RCS to the demultiplexer 222 according to the magnitude of the feedback voltage RVD to further adjust the reference tracking voltage RVS in the linear regulator 220. And make the reference tracking voltage RVS as close as possible to the feedback voltage RVD. In other words, the demultiplexer 222 reduces the voltage difference between the feedback voltage RVD and the reference tracking voltage RVS according to the reference control signal RCS.

When the voltage across the source N pole of the first N-type transistor is too large, the demultiplexer 222 is selectively electrically connected to the reference output voltage ROV according to the reference control signal RCS. Then, the potential of the node n1 is equal to the reference reference voltage VREF plus the reference output voltage ROV, and because the relationship of the virtual short circuit of the amplifier OP causes the reference tracking voltage RVS to be equal to the potential of the node n1, that is, the reference tracking voltage RVS rises by one reference. The magnitude of the output voltage ROV can further reduce the voltage across the source and the drain of the first N-type transistor to achieve energy saving. On the other hand, the potential of one end of the resistor R is the voltage of the node n1, that is, the reference reference voltage VREF plus the reference output voltage ROV, and the potential of the other end of the resistor R is due to the switch design inside the demultiplexer 222. Referring to the output voltage ROV, the voltage across the resistor R is still the reference voltage VREF, which in turn stabilizes the reference current RI.

It is worth mentioning that the reference output voltage ROV stabilized by the storage capacitor SC can be provided to other circuit blocks (not shown in FIG. 3), such as providing a bias voltage. In addition, when the multiplexer 222 is electrically connected to the reference output voltage ROV, the present disclosure is more capable of recovering the reference current RI and providing it to other circuit blocks or components for use, which makes the disclosure economical and environmentally friendly. Current demand.

In order to teach the operation flow of the backlight module of the present invention in more detail, another schematic diagram will be further described below for further detailed description.

[Another embodiment of the backlight module]

Please refer to FIG. 4. FIG. 4 is a backlight module according to still another embodiment of the present invention. The specific circuit diagram. Different from the above embodiment of FIG. 3, the light emitting unit 210 includes LED series DS1~DSN, wherein the LED strings of each channel are formed by connecting at least one light emitting diode, so each The LED strings DS1~DSN of the channel may have different turn-on voltages from each other. The linear regulator 220 includes first N-type transistors MOS1 to MOSN, amplifiers OP1 to OPN, resistors R1 to RN, and demultiplexers 2221 to 222N. The voltage stabilizing unit 240 includes storage capacitors SC1 S SCM, where M and N are positive integers. In the present embodiment, it is assumed that M is equal to N, but is not limited to this embodiment.

The output terminals of each of the LED strings DS1~DSN output the feedback voltages VD1~VDN to the corresponding drains of the first N-type transistors MOS1~MOSN, the LED driver controller 231 and the analog-to-digital digits. Circuit 232. The input end of each of the LED strings DS1~DSN receives the dimming driving voltage VLED, and the output terminals of each of the LED strings DS1~DSN output the reference currents I1~IN. The drains of the first N-type transistors MOS1 to MOSN receive the feedback voltages VD1 to VDN and the reference currents I1 to IN, and the source outputs of the first N-type transistors MOS1 to MOSN are referenced to follow the voltages VS1 to VSN. The positive input terminal and the negative input terminal of each of the amplifiers OP1~OPN respectively receive the reference reference voltage VREF and the reference follow-up voltage VS1~VSN, and the output ends of the amplifiers OP1~OPN are electrically connected to the first N-type transistors MOS1~NOSN, respectively. The gate. One end of each of the resistors R1 to RN respectively receives the reference tracking voltages VS1 to VSN, and the other ends of the resistors R1 to RN respectively output the reference currents I1 to IN. Each of the demultiplexers 2221 to 222N is electrically connected to the negative end of the reference voltage VREF and the other end of each of the resistors R1 to RN, wherein each of the demultiplexers 2221 to 222N can be implemented using at least one switch. One end of the storage capacitor SC1~SCN It is electrically connected to the reference output voltage V1~VM to stabilize the voltage. The other end of the storage capacitors SC1~SCN is electrically connected to the ground voltage GND. What will be further explained next is the operation of the backlight module 400.

Referring to FIG. 4, when the LED driving controller 231 transmits the dimming control signal DCS to the second N-type transistor Mn2, the second N-type transistor Mn2 is turned on according to the dimming control signal DCS or shut down. Further, the size of the dimming driving voltage VLED is determined according to the length of the opening time of the second N-type transistor Mn2, that is, the dimming control signal DCS determines the dimming by means of Pulse Width Modulation (PWM). The driving voltage VLED is driven to drive the LED strings DS1 to DSN. Then, the LED strings DS1~DSN generate corresponding reference currents I1~IN and corresponding feedback voltages VD1~VDN according to the received dimming driving voltage VLED, and respectively correspond the feedback voltages VD1~VDN. The signal is transmitted to the LED driver controller 231, the analog-to-digital circuit 232, and the drains of the first N-type transistors MOS1 to MOSN.

Next, due to component characteristics or process relationships of the light-emitting diodes, the light-emitting diodes may have different turn-on voltages with each other, and thus the light-emitting diode strings DS1 to DSN of each channel may have different turn-on voltages with each other. Further, the feedback voltages VD1 to VDN of each channel are different from each other. Therefore, the LED driver controller 231 determines whether the LED strings DS1~DSN have been completely driven according to the received feedback voltages VD1~VDN, that is, determines the LED string DS1~ Whether the DSN is all lit or all are working properly. If the LED strings DS1~DSN are not fully illuminated, the LED driver controller 231 adjusts the dimming control signal DCS according to the feedback voltages VD1~VDN, that is, increases the pulse width modulation signal. Duty ratio The dimming driving voltage VLED is increased to drive the LED strings DS1 to DSN. The LED driver controller 231 of the embodiment continuously corrects the duty ratio of the pulse width modulation signal by using the feedback mechanism until the LED strings DS1 to DSN are all turned on or all lit.

Next, in the same manner as the embodiment of FIG. 3 described above, the backlight module 400 activates an action related to the energy saving mechanism. In detail, the step-down circuit 233 steps down the received input voltage VIN to the reference output voltages V1 to VM, and stabilizes the plurality of reference output voltages V1 to VM by using the plurality of storage capacitors SC1 to SCM, respectively. . In other words, the plurality of reference output voltages V1 to VM stored in the plurality of storage capacitors SC1 to SCM in the voltage stabilizing unit 240 are supplied by the current (or the supplied energy) supplied from the input voltage VIN. In this embodiment, after the LED arrays DS1 to DSN are completely lit, when the demultiplexers 2221 to 222N are respectively based on the plurality of reference control signals RCS1 to RCSN, respectively, the selection is electrically connected to the corresponding reference respectively. Part or all of the output voltages V1~VN, and some or all of the reference currents I1~IN will flow to other circuit blocks or components via their corresponding demultiplexers 2221~222N, thereby recovering the current I1~IN Part of it to achieve energy saving effect. On the other hand, when the demultiplexers 2221 to 222N are selectively electrically connected to the ground voltage GND according to their corresponding reference control signals RCS1 to RCSN, it means that no operation of recovering the reference currents I1 to IN is performed.

Further, the LED driver controller 231 outputs the reference control signals RCS1 to RCSN to the corresponding demultiplexers 2221 to 222N according to the magnitudes of the feedback voltages VD1 VVDN to further adjust the linear regulator 220. The reference tracking voltages VS1~VSN within the reference tracking voltages VS1~VSN can be as close as possible to the corresponding feedback voltages VD1~VDN. In other words, the demultiplexers 2221 to 222N reduce the voltage difference between the feedback voltages VD1 to VDN and their corresponding reference tracking voltages VS1 to VSN according to the reference control signals RCS1 to RCSN. Therefore, in the present embodiment, even if the light-emitting diodes are different in conduction voltage between each other due to component characteristics or process relationships, and thus the feedback voltages VD1 to VDN of each channel are different from each other, the present disclosure can still The source-drain across the first N-type transistors MOS1 to MOSN is dynamically adjusted to reduce energy consumption and buffer the overheating of the transistor.

In other words, the light-emitting diodes used in the prior art must first determine which forward voltage group to use to ensure that the forward bias voltage of each light-emitting diode string is the same. . Because, if the forward bias voltage of each LED string is different, an excessive voltage drop will occur in the transistor, which will cause the transistor to overheat. Therefore, in addition to power consumption, the life of the transistor may be shortened. Or the burnt of the transistor. However, the present disclosure can achieve the aforementioned related problems such as avoiding overheating of the transistor under the light-emitting diodes that do not distinguish the forward bias group through the mechanism taught above.

Incidentally, when the backlight module 400 performs the dimming to the dark state, that is, the reference currents I1 to IN corresponding to the LEDs DS1 to DSN are low, the designer can design the micro. The controller 235 transmits the reference control signals RCS1~RCSN to select the batch to recover the reference currents I1~IN. Therefore, the disclosure provides considerable flexibility for dimming, and does not affect the original role of the backlight module 400. , that is, provide light.

Before the following description is made, it should be explained here that the following description will be made with N equal to three and M equal to three, and it is assumed that the magnitude relationship between the reference output voltages V1 V V3 is V1 > V2 > V3, Those of ordinary skill in the art should be able to analogize other similar embodiments in which N is greater than three or M is greater than three.

When there is an excessive voltage across the source and the drain of the first N-type transistors MOS1 to MOS3, the demultiplexers 2221 to 2223 are electrically connected to the reference output voltage V1 according to the reference control signals RCS1 to RCS3. ~V3 or ground voltage GND. When the multiplexers 2221~2223 are electrically connected to the reference output voltages V1~V3 according to the reference control signals RCS1~RCS3, the potentials of the nodes n11~n13 are respectively equal to the reference reference voltage VREF plus the reference output voltages V1~V3. . Furthermore, because the relationship between the virtual short circuits of the amplifiers OP1~OP3 causes the reference tracking voltages VS1~VS3 to be equal to the potentials of the nodes n11~n13, that is, the reference tracking voltages VS1~VS3 respectively correspond to the magnitudes of the rising reference output voltages V1~V3, and further The voltage across the source and the drain of the first N-type transistors MOS1 to MOS3 can be reduced. On the other hand, in the same way, the voltage across the two ends of the resistors R1 to R3 is still the reference voltage VREF, and the reference currents I1 to I3 can still be stabilized.

In addition, when the multiplexers 2221~2223 are electrically connected to the reference output voltages V1~V3 according to the reference control signals RCS1~RCS3, the reference currents I1~I3 can be supplied to other circuit blocks or components (not depicted in FIG. 4). Show) use.

[An embodiment of the display device]

Please refer to FIG. 5. FIG. 5 is a schematic diagram of a display device having a backlight module according to an embodiment of the present invention. The display device 500 includes a backlight module 510 and a display panel 520. The backlight module 510 is configured to provide light and the display panel is configured to display image data. The power source used by the backlight module 510, that is, the input voltage VIN, may be the system voltage used in a general display device. The backlight module 510 can be one of the backlight modules 200, 300, and 400 in the above embodiments of FIGS. 2 to 4. The display device 500 can be a display device for displaying image data in various types of electronic devices, that is, a display device 500 is a self-illuminating element (such as a light emitting diode) for providing light.

[An embodiment of the driving method]

Please refer to FIG. 6. FIG. 6 is a flowchart of a driving method according to an embodiment of the present invention. In this embodiment, the driving method of the backlight module includes the following steps. According to the feedback voltage, the reference control signal is output (step S610), that is, the drive control unit outputs at least one reference control signal to the linear regulator according to at least one feedback voltage of the illumination unit. The voltage difference between the feedback voltage and the reference tracking voltage is adjusted according to the reference control signal (step S620), that is, the linear regulator adjusts the voltage difference between the feedback voltage and the reference tracking voltage according to the reference control signal. The details of each step of the driving method of the backlight module have been described in detail in the above embodiments of FIGS. 2 to 5, and will not be described herein. It should be noted that the steps of the embodiment of FIG. 6 are only for convenience of description, and the embodiments of the present invention do not take the steps of the steps as the limitation of implementing various embodiments of the present invention.

[Possible effects of the examples]

In summary, the display device, the backlight module, the driving circuit, and the driving method thereof are provided by the embodiments of the present invention, and the disclosed content can not only recover the reference current output by the light emitting unit, but also provide other circuit blocks or The component is used, and the linear regulator in the disclosure can reduce the voltage difference between the feedback voltage and the reference tracking voltage by referring to the output voltage, thereby reducing the power consumption of the linear regulator, thereby achieving the effect of saving power and saving energy. .

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the invention.

100‧‧‧Study backlight module

200, 300, 400‧‧‧ backlight module

210‧‧‧Lighting unit

220‧‧‧ linear regulator

222, 2221~222N‧‧ ‧ multiplexer

230‧‧‧Drive Control Unit

231‧‧‧Lighting diode drive controller

233‧‧‧Buck circuit

232, 234‧‧‧ analog to digital circuit

235‧‧‧Microcontroller

240‧‧‧Stabilizer

250‧‧‧ dimming unit

500‧‧‧ display device

510‧‧‧Backlight module

520‧‧‧ display panel

AIS‧‧‧ analog signal

DC‧‧‧ dimming capacitor

D1‧‧‧ diode

DS, DS1~DSN‧‧‧Light diode strings

DCS‧‧‧ dimming control signal

DIS1, DIS2‧‧‧ digital signal

GND‧‧‧ Grounding voltage

L1‧‧‧Inductance

Mn1, MOS1~MOSN‧‧‧first N-type transistor

Mn2‧‧‧Second N-type transistor

N1, n11~n1N‧‧‧ nodes

OP, OP1~OPN‧‧‧Amplifier

S610, S620‧‧‧ steps

SC, SC1~SCM‧‧‧ storage capacitor

R, R1~RN‧‧‧ resistance

RI, I1~IN‧‧‧ reference current

ROV, V1~VM‧‧‧ reference output voltage

RCS, RCS1~RCSN‧‧‧ reference control signals

RVD, VD1~VDN‧‧‧ feedback voltage

RVS, VS1~VSN‧‧‧ reference tracking voltage

VREF‧‧‧ reference voltage

VIN‧‧‧ input voltage

VLED‧‧‧ dimming drive voltage

The invention has been described in detail with reference to the accompanying drawings, in which FIG. 1 is a schematic diagram of a conventional backlight module.

2 is a schematic diagram of a backlight module according to an embodiment of the invention.

3 is a detailed view of a backlight module in accordance with an embodiment of the present invention.

4 is a detailed circuit diagram of a backlight module according to still another embodiment of the present invention.

FIG. 5 is a schematic diagram of a display device having a backlight module according to an embodiment of the present invention.

6 is a flow chart of a driving method in accordance with an embodiment of the present invention.

200‧‧‧Backlight module

210‧‧‧Lighting unit

220‧‧‧ linear regulator

230‧‧‧Drive Control Unit

240‧‧‧Stabilizer

250‧‧‧ dimming unit

GND‧‧‧ Grounding voltage

RI‧‧‧reference current

ROV‧‧‧ reference output voltage

RCS‧‧‧ reference control signal

RVD‧‧‧ feedback voltage

RVS‧‧‧ reference tracking voltage

DCS‧‧‧ dimming control signal

VIN‧‧‧ input voltage

VLED‧‧‧ dimming drive voltage

Claims (18)

A backlight module includes: a light emitting unit that outputs at least one feedback voltage and at least one reference current; a linear regulator electrically connected to the light emitting unit, the linear regulator receives and stabilizes the reference current; and a driving a control unit electrically connected to the light emitting unit, the drive control unit receiving and outputting at least one reference control signal to the linear regulator according to the feedback voltage, wherein the linear regulator has at least one reference tracking voltage, and according to the reference A control signal adjusts a voltage difference between the feedback voltage and the reference tracking voltage. The backlight module of claim 1, further comprising: a voltage stabilizing unit for stabilizing the at least one reference output voltage output by the driving control unit. The backlight module of claim 1, further comprising: a dimming unit electrically connected between the driving control unit and the lighting unit, wherein the dimming unit is configured to receive an input voltage and a dimming And controlling a signal, and outputting a dimming driving voltage according to the dimming control signal. The backlight module of claim 2, wherein the linear regulator is selectively electrically connected to the reference output voltage or a ground voltage according to the reference control signal. The backlight module of claim 4, wherein the linear regulator comprises: at least one demultiplexer, and is selectively electrically connected to the reference output voltage or the ground voltage according to the reference control signal. The backlight module of claim 4, wherein the driving control sheet The element further outputs a plurality of the reference output voltages, and the linear regulator reduces the voltage difference between the feedback voltage and a reference tracking voltage by selectively connecting to one of the plurality of reference output voltages. The backlight module of claim 3, wherein the light emitting unit comprises: at least one light emitting diode string, the output end of which outputs the feedback voltage to the linear regulator and the driving control unit, and the input end thereof Receiving the dimming driving voltage, wherein the output end of the LED string outputs the reference current. The backlight module of claim 5, wherein the linear regulator comprises: at least one first N-type transistor, the drain receiving the feedback voltage and the reference current, and the source outputting the reference follow-up a voltage; at least one amplifier, a positive input terminal and a negative input terminal of the amplifier respectively receive the reference reference voltage and the reference follow-up voltage, and the output end thereof is electrically connected to the gate of the first N-type transistor; at least one resistor, One end receives the reference tracking voltage, and the other end outputs the reference current; and wherein the demultiplexer is electrically connected to a negative terminal of the reference reference voltage and the other end of the resistor, and selects electricity according to the reference control signal The voltage is connected to the reference output voltage or the ground voltage to adjust a voltage difference between the feedback voltage and the reference tracking voltage. The backlight module of claim 3, wherein the driving control unit comprises: a light emitting diode driving controller for receiving the feedback voltage, and outputting the dimming control signal according to the feedback voltage a first analog-to-digital circuit for receiving the feedback voltage and delivering the feedback The voltage is converted into a first digital signal; a step-down circuit is configured to receive the input voltage and step down the input voltage to a reference output voltage; a second analog-to-digital circuit electrically connected to the step-down circuit The second analog-to-digital circuit receives an analog signal and converts it into a second digital signal; and a microcontroller electrically coupled to the first analog-to-digital circuit and the second analog-to-digital circuit, the microcontroller Receiving and outputting the reference control signal to the demultiplexer according to the first digital signal and the second digital signal. The backlight module of claim 3, wherein the dimming unit comprises: an inductor, one end of which receives the input voltage; and a second N-type transistor whose pole is electrically connected to the other end of the inductor The source is electrically connected to a ground voltage, and the gate receives the dimming control signal; a diode is electrically connected to the other end of the inductor, the negative terminal outputs the dimming driving voltage; and a dimming The capacitor has one end electrically connected to the negative electrode of the diode, and the other end of which is electrically connected to the ground voltage. A driving method is applicable to a backlight module, wherein the backlight module comprises a light emitting unit, a linear regulator and a driving control unit, wherein the linear regulator is electrically connected to the lighting unit, and the driving control unit is electrically connected The illuminating unit, and the driving method includes: using the driving control unit to output at least one reference control signal to the linear regulator according to at least one feedback voltage of the illuminating unit; and using the linear regulator to have at least one reference tracking voltage And according to the reference And a control signal that adjusts a voltage difference between the feedback voltage and the at least one reference tracking voltage. The driving method of claim 11, further comprising: using the linear regulator to selectively connect to the reference output voltage or a ground voltage according to the reference control signal. The driving method of claim 11, wherein the backlight module further comprises a dimming unit electrically connected between the driving control unit and the lighting unit, and the driving method further comprises: using the dimming The unit receives an input voltage and a dimming control signal; and outputs a dimming driving voltage according to the dimming control signal by using the dimming unit. a driving circuit for driving at least one light emitting diode, the light emitting diode outputting at least one feedback voltage and at least one reference current, the driving circuit comprising: a linear regulator electrically connected to the light emitting diode The linear regulator is configured to receive and stabilize the reference current; and the driving control unit is electrically connected to the light emitting diode, and the driving control unit receives and outputs at least one reference control signal to the linear regulator according to the feedback voltage, Wherein the linear regulator has at least one reference tracking voltage, and adjusts a voltage difference between the feedback voltage and the at least one reference tracking voltage according to the reference control signal. The driving circuit of claim 14, further comprising: a voltage stabilizing unit for stabilizing the at least one reference output voltage output by the driving control unit. The driving circuit of claim 15, wherein the linear regulator is selectively electrically connected to the reference output voltage or a ground voltage according to the reference control signal. The driving circuit of claim 16, wherein the linear regulator comprises: at least one demultiplexer, and is selectively electrically connected to the reference output voltage or the ground voltage according to the reference control signal. The driving circuit of claim 16, wherein the driving control unit further outputs a plurality of the reference output voltages, and the linear regulator adjusts the electrical connection by electrically connecting one of the plurality of reference output voltages. The voltage difference between the feedback voltage and a reference tracking voltage.