Backlight module, voltage control method, driving method and device thereof and liquid crystal display equipment

Abstract

The invention discloses a backlight module, a voltage control method, a driving method and device thereof and liquid crystal display equipment. The driving device is suitable for providing control channel currents matched with the current areas where the light-emitting units are located for the light-emitting units in the different current areas so as to drive the light-emitting units in the different current areas to emit light in the same frame in a time-sharing mode. The voltage control method comprises the following steps: in a frame, acquiring the voltage corresponding to the feedback network at the voltage feedback node when the light-emitting unit emits light in each current area, and based on the acquired voltage, providing a working voltage matched with the acquired voltage for the light-emitting unit in each current area. By adopting the scheme, the temperature rise of the LED driving chip can be realized.

Description

Technical Field

[0001] The present invention relates to the field of liquid crystal display, and in particular to a backlight module and a voltage control method, a driving method, a device and a liquid crystal display device thereof. Background Art

[0002] Local dimming (LD) is a backlight control technology used in liquid crystal displays. Compared with traditional backlight, a liquid crystal display based on LD backlight includes an LED matrix consisting of M rows and N columns of light-emitting diodes (LEDs). The LED matrix conventionally adopts a common anode architecture, that is, the anodes of all LEDs are connected in parallel and connected to the working voltage output terminal of an external power management module, which powers the LEDs.

[0003] Among them, the LED matrix with multi-scan architecture usually connects a Metal Oxide-Semiconductor Field Effect Transistor (MOS) tube in series between the anode of the LED light-emitting diode and the working voltage output end of the external power management module of the power supply, and realizes the multi-scan function by controlling the switch of the MOS tube.

[0004] However, the heat loss of the conventional common anode LED matrix is ​​relatively high, resulting in a relatively high temperature rise of the LED driver chip. Summary of the invention

[0005] The problem to be solved by the present invention is to reduce the temperature rise of the LED driver chip.

[0006] To solve the above problems, an embodiment of the present invention provides a voltage control method for a backlight module, the backlight module comprising: an LED matrix, a feedback network and a driving device; the LED matrix comprises two or more current regions, and the same current region comprises at least one light-emitting unit group; each light-emitting unit group comprises at least one light-emitting unit; the feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current region;

[0007] The driving device is suitable for providing the light-emitting units in different current regions with control channel currents matching the current regions in which they are located, so as to drive the light-emitting units in different current regions to emit light in a time-sharing manner within the same frame;

[0008] Voltage control methods include:

[0009] In one frame, the voltage at the voltage feedback node of the feedback network corresponding to the light emitting unit in each current region is collected when the light emitting unit in each current region emits light, and based on the collected voltage, an operating voltage matching the collected voltage is provided to the light emitting unit in each current region.

[0010] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0011] By applying the voltage control scheme in the embodiment of the present invention, in the process of driving the light-emitting units in different current regions to emit light in a time-sharing manner within the same frame, since the working voltage provided to the light-emitting units in each current region in each frame matches the actual required voltage of the light-emitting units, the voltage on the cathode of the light-emitting unit can be reduced in each frame, reducing heat loss, thereby improving the working efficiency of the power supply and reducing the temperature rise of the LED driver chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a curve diagram showing the change of the forward current of LED with the forward voltage drop;

[0013] Figure 2 is a structural schematic diagram of a backlight module in an embodiment of the present invention;

[0014] Figure 3 is a flow chart of a voltage control method in an embodiment of the present invention;

[0015] Figure 4 is a schematic diagram of a current region of an LED matrix in an embodiment of the present invention;

[0016] Figure 5 It is a timing diagram of related signals in the process of light emission of an LED matrix in an embodiment of the present invention;

[0017] Figure 6 is a schematic structural diagram of a power management device in an embodiment of the present invention;

[0018] Figure 7 It is a schematic diagram of the operating voltage output by the power management device changing with time;

[0019] Figure 8 is a schematic structural diagram of another backlight module in an embodiment of the present invention;

[0020] Fig. 9 is a flow chart of a method for driving a backlight module in an embodiment of the present invention;

[0021] Fig.10 is a timing diagram of related signals in another LED matrix light-emitting process according to an embodiment of the present invention;

[0022] Fig.11It is a structural schematic diagram of a driving device of a backlight module in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] Currently, in an LED matrix with a common anode architecture, the anode voltages of the various LEDs are always kept consistent.

[0024] However, due to the different working conditions of different LEDs, the required forward voltage drop is also different. Figure 1 is the forward current I of the LED f With the forward voltage drop V f Schematic diagram of the changing curve. Figure 1 , LED forward voltage drop V f The forward current I f is positively correlated, and the LED forward current I f It is positively correlated with the brightness of the LED. The so-called forward voltage drop of the LED refers to the forward voltage drop of the LED under the specified forward current, which is the minimum forward voltage that the LED can conduct. The opposite of the forward voltage drop of the LED is the reverse voltage drop of the LED, that is, the voltage drop at both ends of the LED when it is connected in reverse. Therefore, the forward voltage drop required for LEDs in different working states is also different.

[0025] However, the LED matrix driver does not have the ability to adjust the LED cathode voltage. When the anode voltage is greater than the required voltage drop, the LED cathode voltage will be greater than the ideal voltage due to automatic matching of the voltage drop. As a result, in the entire common anode LED matrix, except for the brightest LED, the cathode voltage of each LED is greater than the theoretically required voltage. This excess voltage will be consumed in the form of heat, resulting in a higher temperature rise in the LED driver chip.

[0026] For example, when the forward current of the edge area light emitting element in the LED matrix is ​​40mA, and the forward current of the center area light emitting element is 20mA, then the voltage drop of the edge area light emitting element is 6.0V, and the voltage drop of the center area light emitting element is 5.7V. The voltage drop is the voltage difference between the anode and cathode of the light emitting element. At this time, if the voltage provided to the anode of the light emitting element is 7V, the cathode voltage of the edge area light emitting element is 1V, and the cathode voltage of the center area light emitting element is 0.5V. Ideally, the cathode voltage should be 0V, so the extra voltage of the cathode of the light emitting element is wasted in the form of heat.

[0027] To address this problem, the present invention provides a voltage control method for a backlight module, in which an LED matrix includes two or more current regions, and a driving device can drive light-emitting units in different current regions to emit light in a time-sharing manner within the same frame, wherein a power management device provides an operating voltage for the light-emitting units in each current region that matches their actual required voltage, thereby reducing the voltage on the cathode of the light-emitting unit and reducing heat loss, thereby improving the power supply working efficiency and reducing the temperature rise of the LED driver chip.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Figure 2 FIG. 2 is a schematic diagram of the structure of a backlight module 20 in one embodiment of the present invention. Figure 2 The backlight module 20 may include: an LED matrix 21, a feedback network 22, a power management device 23 and a driving device 24. Figure 2 The arrows in the middle indicate the current flow direction at the corresponding nodes.

[0030] The LED matrix 21 may include two or more current regions, and the same current region includes at least one light-emitting unit group, and each light-emitting unit group includes at least one light-emitting unit. Each light-emitting unit may be composed of a single light-emitting element. Figure 2 As shown, the light emitting element may be a light emitting diode, and each of the light emitting unit groups includes at least one light emitting diode.

[0031] For example, the LED matrix may be divided into two current regions, three current regions or four current regions, each current region may include 8 light emitting unit groups, and each light emitting unit group may include 10 light emitting units.

[0032] In one embodiment, referring to Figure 4 The LED matrix 21 can be divided into two current regions, namely a first current region 211 (i.e., a dark region) and a second current region 212 (i.e., a light region). The control channel current of the light-emitting unit in the first current region 211 is a first current, and the control channel current of the light-emitting unit in the second current region 212 is a second current. The first current is greater than the second current.

[0033] In one embodiment, the first current region 211 is an edge region of the backlight module 20. The second current region 212 is a non-edge region of the backlight module 20. The second current region 212 is located in the first current region 211, and the first current region 211 surrounds the second current region 212. In this way, the light-emitting units in the edge region of the LED matrix 21 are set as large current regions, and the light-emitting units in other regions of the LED matrix 21 are set as small current regions, which is more in line with the actual application scenario of the LED matrix, and is conducive to providing different operating voltages for different current regions in the future, which can not only meet the operating voltage requirements of different current regions, but also reduce the temperature rise.

[0034] In a specific implementation, the power management device 23 is used to provide operating voltage for the light-emitting elements in each current region of the LED matrix 21 .

[0035] In a specific implementation, a plurality of switching elements 25 are arranged between the power management device 23 and the LED matrix 21. The light-emitting units in the same light-emitting unit group of the LED matrix 21 can be connected to the working voltage output terminal V0 of the power management device 23 through the same switching element. Thus, whether the light-emitting units in the entire light-emitting unit group emit light can be controlled by controlling the on and off of the switching elements.

[0036] In a specific implementation, a feedback network 22 is further provided between the power management device 23 and the LED matrix 21. The feedback network 22 is connected to the voltage collection terminal Vout of the LED matrix 21. The feedback network has a voltage feedback node A, and the voltage at the voltage feedback node A is used to feedback the actual required voltage of the light-emitting unit in the current current range.

[0037] In a specific implementation, the feedback network 22 can be implemented using a variety of circuit structures. Figure 2 The feedback network 22 may include two first resistors R1 and second resistors R2 connected in series, the connection point between the first resistor R1 and the second resistor R2 is used as a voltage feedback node A, the other end of the first resistor R1 is connected to the voltage collection terminal Vout of the LED matrix 21, and the other end of the second resistor R2 is grounded. The voltage feedback node A is connected to the voltage feedback terminal FB2 of the power management device 23.

[0038] In a specific implementation, the driving device 24 can provide the light-emitting units in different current regions of the LED matrix 21 with control channel currents that match the current regions in which they are located, thereby driving the light-emitting units in different current regions to emit light.

[0039] Specifically, the driving device 24 may include a plurality of control units, each of which includes a plurality of control channels (such as control channel S1 and control channel S2), time-sharing ports (such as time-sharing port K1 and time-sharing port K2), and feedback port FB1. One control channel can control a plurality of light-emitting elements, but the plurality of light-emitting elements controlled by the same control channel belong to different current regions respectively. In the same current region, the light-emitting elements correspond to the control channels one by one. One time-sharing port corresponds one by one to a light-emitting unit group, that is, one time-sharing port drives one light-emitting unit group. The control channel can provide the corresponding light-emitting element with a control channel current matching the current region in which it is located, and then the switch element of the light-emitting unit group is controlled to be turned on through the time-sharing port, so that the single light-emitting unit group can emit light.

[0040] Taking the switching element as a MOS tube and the light-emitting element as a light-emitting diode as an example, the control channel is connected to the cathode of the light-emitting diode, the anode of the light-emitting diode is connected to the source of the switching element, the gate of the switching element is connected to the time-sharing port, and the drain of the switching element is connected to the voltage collection terminal Vout of the LED matrix 21. The voltage collection terminal Vout of the LED matrix 21 is connected to the working voltage output terminal V0 of the power management device 23, and the feedback port FB1 is connected to the voltage feedback node A and the voltage feedback terminal FB2 of the power management device 23.

[0041] Reference Figure 2 and Figure 4 Assume that in the initial state, the power management device 23 outputs the working voltage V' through the voltage collection terminal Vout of the LED matrix. In one frame, the driving device can control the first current region 211 and the second current region 212 to emit light alternately through the time-sharing port K1 and the time-sharing port K2.

[0042] When controlling the first current region 211 to emit light, the driving device 24 can output a high-level signal to the MOS tube Q1 through the time-sharing port K1, and output a low-level signal to the MOS tube Q2 through the time-sharing port K2. At this time, the MOS tube Q1 is turned on, the MOS tube Q2 is turned off, the light-emitting unit in the first current region 211 emits light, and the light-emitting unit in the second current region 212 does not emit light.

[0043] In the light-emitting stage of the light-emitting unit in the first current region 211, the power management device 23 monitors the voltage of the voltage feedback node A in real time through the feedback network, and obtains the actual required voltage of the light-emitting unit based on the voltage of the voltage feedback node A, thereby adjusting the operating voltage provided to the light-emitting unit in the first current region 211. In the light-emitting stage of the light-emitting unit in the second current region 212, the power management device 23 monitors the voltage of the voltage feedback node A in real time through the feedback network, and obtains the actual required voltage of the light-emitting unit based on the voltage of the voltage feedback node A, thereby adjusting the operating voltage provided to the light-emitting unit in the second current region 211.

[0044] Among them, the voltage VA of the voltage feedback node A = Vout*R2 / (R1+R2). Based on VA, the value of Vout can be obtained, that is, the voltage value collected by the voltage collection end of the LED matrix. The value of Vout can be compared with the preset reference voltage Vth. When Vout < Vth, it indicates that the current working voltage of the power management device 23 is small, and the working voltage can be increased at this time. When Vout > Vth, it indicates that the current working voltage of the power management device 23 is large, and the working voltage can be reduced at this time, and finally Vout = Vth, so that each light-emitting unit remains in a steady state.

[0045] The driving device 24 can also obtain the voltage of the voltage feedback node A through the voltage feedback terminal FB2, thereby knowing the actual required voltage in the current region, so as to perform other control operations based on the actual required voltage.

[0046] In the embodiment of the present invention, the driving device 24 is suitable for providing the light-emitting units in different current regions with control channel currents matching the current regions, thereby driving the light-emitting units in different current regions to emit light in time-sharing within the same frame. The so-called time-sharing light emission within the same frame means that the light-emitting units in each current region emit light at different times within a frame, and only one light-emitting unit in a current region emits light at the same time within a frame, and the specific light emission order is not limited.

[0047] Accordingly, refer to Figure 3 The embodiment of the present invention further provides a voltage control method, which may include the following steps:

[0048] Step 31 , within one frame, collecting the voltage at the voltage feedback node of the feedback network corresponding to when the light-emitting unit in each current region emits light.

[0049] Step 32: Based on the collected voltage, provide the light-emitting units in each current region with an operating voltage that matches the collected voltage.

[0050] Specifically, the power management device 23 can collect the voltage corresponding to the voltage at the voltage feedback node A of the feedback network 22 when the light-emitting unit in each current region emits light through the voltage feedback node within one frame, and based on the collected voltage, provide the light-emitting unit in each current region with an operating voltage that matches the collected voltage.

[0051] The driving device 24 can drive the light-emitting units in all current regions to emit light in time within a frame, that is, the light-emitting units in different current regions emit light in time within a frame, and only one light-emitting unit in a current region emits light at the same time within a frame. The specific light-emitting sequence is not limited, for example, the light-emitting units can emit light alternately or in a specific sequence. The power management device 23 can provide a working voltage that matches the actual demand for each light-emitting unit in the current region, thereby reducing the voltage on the cathode of the light-emitting unit in each frame, reducing heat loss, thereby improving the power supply working efficiency and reducing the temperature rise of the LED driver chip.

[0052] For example, refer to Figure 2 When the driving device 24 drives the light-emitting unit in the first current region to emit light, it controls the switch tube Q1 to be turned on, and the working voltage terminal V0 of the power management device 23, the switch tube Q1, the light-emitting unit P1 and the control channel S1 of the driving device 24 form a current path. Since the control channel current of the light-emitting unit in the first current region is relatively large, when the impedance of the wire between the LED matrix voltage collection terminal Vout and the working voltage terminal V0 of the power management device 23 remains unchanged, the voltage of the LED matrix voltage collection terminal Vout will drop, and the voltage of the voltage collection terminal Vout will affect the current value flowing through the feedback network, thereby changing the voltage of the voltage feedback node A. In this way, the power management device 23 can obtain the actual required voltage of the light-emitting unit by monitoring the voltage of the voltage feedback node A.

[0053] In one embodiment of the present invention, when the power management device 23 provides a working voltage that matches the actual demand for each light-emitting unit in the current region of light, the collected voltage can be compared with the preset reference voltage, and then based on the difference between the collected voltage and the preset reference voltage, the working voltage can be provided for the light-emitting unit in the current current region, so that the collected voltage is equal to the preset reference voltage, thereby making the actual required voltage of each light-emitting unit remain in a steady state. The preset reference voltage is the expected steady-state voltage value of the voltage collection end of the LED matrix, that is, the actual required voltage of the light-emitting unit is equal to the preset reference voltage.

[0054] Since there is a voltage drop on the wire connected to the working voltage output terminal V0 of the power management device 23 and the voltage collection terminal of the LED matrix, the current on the wire also changes with the alternating changes of the current area. In order to ensure that the actual required voltage of each light-emitting unit remains in a steady state, when the light-emitting unit emits light in different current areas, the working voltage output by the working voltage output terminal V0 of the power management device 23 needs to change. The working voltage output by the working voltage output terminal of the power management device 23 needs to match the actual required voltage of each light-emitting unit to ensure that the actual required voltage of each light-emitting unit remains in a steady state.

[0055] Specifically, when the collected voltage is less than the preset reference voltage, the power management device 23 can provide a first operating voltage for the light-emitting unit in the current current region, the first operating voltage is greater than the preset reference voltage, at this time, by increasing the operating voltage, the actual required voltage of each light-emitting unit is kept in a steady state, that is, the actual required voltage of the light-emitting unit is equal to the preset reference voltage. When the collected voltage is greater than the preset reference voltage, a second operating voltage is provided for the light-emitting unit in the current current region, the second operating voltage is less than the first operating voltage, at this time, by reducing the operating voltage, the actual required voltage of each light-emitting unit is kept in a steady state.

[0056] In a specific implementation, the specific values ​​of the first working voltage and the second working voltage can be set according to the control channel current in the current current range and the impedance of the wire connected to the working voltage output terminal V0 of the power management device 23 and the voltage collection terminal of the LED matrix.

[0057] When the light-emitting units emit light in different current regions, the power management device 23 provides an operating voltage that matches the actual demand, which can meet the voltage requirements of the light-emitting units in different current regions, thereby improving the energy efficiency of the entire backlight module 20 and reducing the temperature rise of the driving device.

[0058] by Figure 3 For example, refer to Figure 2 and Figure 4 , the light-emitting unit P1 in the first current region 211 is connected to the working voltage output terminal V0 of the power management device 23 through the MOS transistor Q1, and the light-emitting unit P2 in the second current region 212 is connected to the working voltage output terminal V0 of the power management device 23 through the MOS transistor Q2. The gate of the MOS transistor Q1 is connected to the time-sharing port K1, and the gate of the MOS transistor Q2 is connected to the time-sharing port K2. The source of the light-emitting unit P1 is connected to the control channel S1 of the driving device 24, and the source of the light-emitting unit P2 is connected to the control channel S2 of the driving device 24.

[0059] Figure 5 for Figure 2 The timing diagram of the relevant signals in the LED matrix lighting process. Figure 5 , the driving device 24 controls the first current region 211 and the second current region 212 to emit light in the same frame in time division. The driving device 24 provides a control channel current Ilarge for the light emitting unit P1 in the first current region 211, and provides a control channel current Ismall for the light emitting unit P2 in the second current region 212, where Ilarge is greater than Ismall.

[0060] Specifically, in the first frame, the driving device 24 drives the light-emitting unit P1 in the first current region 211 to emit light. Since the control channel currents of the light-emitting units in different current regions are different, the voltage drop of the wire between the LED matrix voltage collection end and the power management device 23 will be different, thereby causing the voltage at the LED matrix voltage collection end to change. The power management device 23 can obtain the voltage of the voltage collection end through the voltage feedback node, and then obtain the actual required voltage of the light-emitting unit in the current region of the current that is currently emitting light. Normally, when the first current region 211 emits light, the collected voltage will be less than the preset reference voltage. For this reason, the power management device 23 can provide the light-emitting unit P1 in the first current region 211 with a first working voltage V1 to keep the actual required voltage of the light-emitting unit P1 in the first current region 211 in a steady state.

[0061] Afterwards, the driving device 24 drives the light-emitting unit P2 in the second current region 212 to emit light, which will make the collected voltage greater than the preset reference unit. At this time, the power management device 23 can provide a second operating voltage V2 for the light-emitting unit P2 in the second current region 212 to keep the actual required voltage of the light-emitting unit P2 in the first current region 212 in a steady state.

[0062] Likewise, in the second frame, the driving device 24 sequentially drives the light emitting unit P1 in the first current region 211 and the light emitting unit P2 in the second current region 212 to emit light, and provides different operating voltages to the light emitting units in different current regions.

[0063] In order to enable those skilled in the art to better understand and implement the present invention, refer to Figure 6 The embodiment of the present invention further provides a power management device 23, which may include: a collection unit 231 and a voltage control unit 232. Wherein:

[0064] The acquisition unit 231 is adapted to acquire, within one frame, the voltage at the voltage feedback node of the feedback network corresponding to the light emitting unit in each current region emitting light;

[0065] The voltage control unit 232 is adapted to provide a working voltage matching the collected voltage to the light-emitting units in each current region based on the collected voltage.

[0066] In an embodiment of the present invention, the voltage control unit 232 may include: a comparison subunit 2321 and a power supply subunit 2322. Wherein:

[0067] The comparison subunit 2321 is adapted to compare the collected voltage with a preset reference voltage;

[0068] The power supply subunit 2322 is adapted to provide a working voltage for the light-emitting unit in the current current region based on the difference between the collected voltage and the preset reference voltage, so that the collected voltage is equal to the preset reference voltage.

[0069] In one embodiment of the present invention, the electronic power supply unit 2322 is suitable for providing a first operating voltage for the light-emitting unit in the current current region when the collected voltage is less than the preset reference voltage, and the first operating voltage is greater than the preset reference voltage; and when the collected voltage is greater than the preset reference voltage, providing a second operating voltage for the light-emitting unit in the current current region, and the second operating voltage is less than the first operating voltage.

[0070] In one embodiment of the present invention, the LED matrix includes a first current region and a second current region, the control channel current of the light-emitting unit in the first current region is a first current, the control channel current of the light-emitting unit in the second current region is a second current, and the first current is greater than the second current.

[0071] In an embodiment of the present invention, the first current region is an edge region of the backlight module; and the second current region is a non-edge region of the backlight module.

[0072] The inventor has found that in the implementation of the time-sharing drive of the anode voltage of the light-emitting diode, Figure 7 When entering the high voltage stage and the low voltage stage, the working voltage output by the power management device 23 will fluctuate. The brightness of the light emitting element is positively correlated with the working voltage at both ends of the light emitting element, which causes the light emitting element to flicker and affects the light emitting effect.

[0073] To this end, the embodiment of the present invention further provides another backlight module 30. Figure 8 In addition to the LED matrix 21, the feedback network 22, the power management device 23 and the driving device 24, the backlight module 30 may also include a micro control unit 26. The micro control unit 26 is connected to the feedback network 22 and is used to change the voltage of the voltage feedback node A of the feedback network 22 before switching the working voltage of the LED matrix 21.

[0074] In a specific implementation, the micro control unit 26 may have a variety of circuit structures, which are not limited here.

[0075] In an embodiment of the present invention, the micro control unit 26 may include: a micro controller MCU, a micro switch Q0, and a micro resistor R3 connected in parallel with the micro switch Q0; the micro resistor R3 is connected to the feedback network 22; the micro switch Q0 is suitable for opening or closing under the control of the micro controller MCU to change the voltage of the voltage feedback node A of the feedback network 22. The micro switch Q0 may be implemented by a switch device such as a MOS tube.

[0076] Specifically, the micro-control resistor R3 can be connected in series with the first resistor R1 and the second resistor R3. The microcontroller MCU can control the on and off of the micro-control switch Q0 based on an internal program or an external control instruction. When the micro-control switch Q0 is turned on, the micro-control resistor R3 is short-circuited. At this time, the voltage of the voltage feedback node A of the feedback network 22 is: the product of the sum of the resistance values ​​of the first resistor R1 and the second resistor R2 and the corresponding control channel current. When the micro-control switch Q0 is disconnected, the micro-control resistor R3 is connected to the feedback network 22. At this time, the voltage of the voltage feedback node A of the feedback network 22 is: the product of the sum of the resistance values ​​of the first resistor R1, the second resistor R2 and the micro-control resistor R3 and the corresponding control channel current. Therefore, by controlling the on and off of the micro-control switch Q0, the purpose of changing the voltage of the voltage feedback node A can be achieved.

[0077] Reference Fig. 9 The embodiment of the present invention further provides a method for driving a backlight module, and the method may include the following steps:

[0078] Step 91 , before the voltage of the voltage feedback node of the feedback network changes, the currents of all control channels are turned off.

[0079] Step 92, after the voltage change of the voltage feedback node of the feedback network reaches a preset time length, provide the light-emitting units in different current regions with control channel currents matching the current regions, so as to drive the light-emitting units in different current regions to emit light in time-sharing within the same frame.

[0080] Specifically, the driving device 24 can turn off the current of all control channels before the voltage of the voltage feedback node A of the feedback network 22 changes. For example, when the driving device 24 includes four time-sharing channels K1 to K4, before the voltage of the voltage feedback node A of the feedback network 22 changes, that is, before the power management device 23 changes the output working voltage, the switch tubes Q1 to Q4 are turned off through the time-sharing channels K1 to K4, and the control channel current is not provided to each light-emitting element, which is equivalent to not activating the switch tubes Q1 to Q4. After the voltage change of the voltage feedback node A reaches a preset time length, the switch tubes Q1 to Q4 are activated again, and the control channel current is provided to the light-emitting unit in the current area of ​​the current that is currently emitting light through the control channel S1 or the control channel S2.

[0081] In a specific implementation, the preset duration can be set according to the fluctuation duration when the working voltage of the power management device 23 is switched. The preset duration should be greater than or equal to the fluctuation duration after the working voltage of the power management device 23 is switched.

[0082] In one embodiment, the value range of the preset time length is 160us to 240us. For example, the value of the first preset time length can be 160us, 180us, 200us, 220us or 240us.

[0083] Taking the preset duration value of 200us as an example, the driving device 24 can activate the time-sharing channel corresponding to the light-emitting unit in the current area that needs to emit light after the voltage change at the voltage feedback node A reaches 200us, so that the light-emitting unit emits light constantly, avoiding the lighting effect being affected by the unstable working voltage output by the power management device 23.

[0084] In one embodiment, after the voltage change at the voltage feedback node A reaches a preset duration, the driving device 24 sequentially activates the switch tubes corresponding to different light-emitting unit groups in the same current region, and provides the light-emitting units connected to the activated switch tubes with a control channel current matching the current region, so that within one frame, each light-emitting unit group in the same current region emits light at the same time.

[0085] In practical applications, the preset time length that the driving device 24 waits after the voltage at the voltage feedback node A enters a high voltage may be the same as or different from the preset time length that the driving device 24 waits after the voltage at the voltage feedback node A enters a low voltage. Specifically, the driving device 24 waits for a first preset time length after the voltage at the voltage feedback node A enters a high voltage, and waits for a second preset time length after the voltage at the voltage feedback node A enters a low voltage. The first preset time length and the second preset time length may be the same as or different from each other.

[0086] by Figure 4 For example, the LED matrix is ​​divided into a first current region 211 and a second current region 212. Figure 4 and Figure 7 , assuming that light emitting elements P1 and P5 belong to the light emitting elements of the first current region 211, and light emitting elements P2, P3, P4, P6, P7 and P8 belong to the light emitting elements of the second current region 212. The first current region 211 and the second current region 212 operate alternately to maintain the normal operation of the backlight module.

[0087] Specifically, in the operation stage of the first current region 211, the microcontroller MCU outputs a high level to turn on the micro-switch Q0, short-circuit the micro-resistor R3, and the power management device 23 provides the first working voltage for the first current region 211. At this time, the first working voltage is unstable. To avoid flickering of the light-emitting element in the first current region 211, refer to Fig.10 In the first frame, the driving device 24 can wait for the first preset time length Delay1 after the voltage of the voltage feedback node A enters the high voltage, and then control the time-sharing port K1 to output a high level, so that the switching element Q1 is turned on, thereby providing a control channel current for the light-emitting element P1 and the light-emitting element P5 to drive the light-emitting unit in the first current region 211 to emit light.

[0088] In the operation stage of the second current region 212, the microcontroller MCU outputs a low level, the micro-switch Q0 is disconnected, the micro-resistor R3 is not short-circuited, and the power management device 23 provides the second working voltage for the first current region 211. At this time, the second working voltage is unstable. In order to prevent the light-emitting element in the second current region 212 from flickering, the driving device 24 waits for the second preset time length Delay2 after the voltage of the voltage feedback node A enters the low voltage, and then controls the time-sharing ports K2, K3 and K4 to output high levels in sequence, so that other switch elements are turned on, thereby providing control channel current for other switch elements to drive the light-emitting unit in the second current region 212 to emit light constantly.

[0089] The duration of providing the control channel current to each light emitting element can be set according to actual needs, for example, referring to Fig.10 , the duration that control channel S1 provides control channel current to light-emitting element P1 (i.e., the duration of low level) can account for 50% of the entire cycle. When control channel S1 provides control channel current to light-emitting element P2, it can account for 60% of the entire cycle. When control channel S1 provides control channel current to light-emitting element P3, it can account for 40% of the entire cycle. When control channel S1 provides control channel current to light-emitting element P4, it can account for 1% of the entire cycle.

[0090] In order to enable those skilled in the art to better understand and implement the present invention, refer to Fig.11 The embodiment of the present invention further provides a driving device 24 of a backlight module, and the driving device 24 may include: a channel current control unit 241 and a timing unit 242. Wherein:

[0091] The channel current control unit 241 is adapted to shut down the current of all control channels before the voltage of the voltage feedback node of the feedback network changes;

[0092] The timing unit 242 is adapted to time the duration of the change of the voltage of the voltage feedback node of the feedback network;

[0093] The channel current control unit 241 is also suitable for providing the light-emitting units in different current regions with a control channel current matching the current region after the voltage change of the voltage feedback node of the feedback network reaches a preset time length, so as to drive the light-emitting units in different current regions to emit light in time-sharing within the same frame.

[0094] In a specific implementation, the driving device 24 may include multiple channel current control units 241, each of which is connected to a feedback port, a corresponding control channel and a time-sharing port, respectively, thereby controlling the output of the control channel and the time-sharing port to achieve channel current control.

[0095] The channel current control unit 241 and the timing unit 242 may be implemented with reference to the above description of the backlight module driving method, and will not be described in detail here.

[0096] By providing a control channel current matching the current region that needs to emit light after the voltage change at the voltage feedback node of the feedback network reaches a preset time, the light-emitting unit in the current region that needs to emit light can always operate in a constant voltage region, thereby maintaining a stable brightness without flickering, thereby effectively improving the light-emitting effect.

[0097] An embodiment of the present invention further provides a liquid crystal display device, which includes the backlight module in any one of the above embodiments.

[0098] By using the backlight module in the embodiment of the present invention, each current area of ​​the LED matrix can emit light in time within the same frame, and the power management device can provide a matching operating voltage for the current area currently emitting light, thereby reducing the temperature rise of the driving device, thereby reducing the temperature rise of the backlight module.

[0099] Furthermore, the driving device turns off the current of all control channels before the voltage of the voltage feedback node of the feedback network changes, and provides control channel currents matching the current regions to the light-emitting units in different current regions after the voltage change of the voltage feedback node of the feedback network reaches a preset time length, thereby enabling the light-emitting units in each current region to emit constant light, thereby improving the display effect of the liquid crystal display device.

[0100] Regarding the various modules / units included in the various devices and products described in the above embodiments, they can be software modules / units, or hardware modules / units, or they can be partially software modules / units and partially hardware modules / units. For example, for various devices and products applied to or integrated in a chip, the various modules / units included therein can all be implemented in the form of hardware such as circuits, or at least some of the modules / units can be implemented in the form of software programs, which run on a processor integrated inside the chip, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits; for various devices and products applied to or integrated in a chip module, the various modules / units included therein can all be implemented in the form of hardware such as circuits, and different modules / units can be located in the same component (such as a chip, circuit module, etc.) or different components of the chip module, or at least some of the modules / units can be implemented in the form of hardware such as circuits. The element can be implemented in the form of a software program, which runs on the processor integrated inside the chip module, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits; for various devices and products applied to or integrated in the terminal, the various modules / units contained therein can be implemented in the form of hardware such as circuits, and different modules / units can be located in the same component (for example, chip, circuit module, etc.) or different components in the terminal, or, at least some modules / units can be implemented in the form of a software program, which runs on the processor integrated inside the terminal, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits.

[0101] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A voltage control method for a backlight module, characterized in that: The backlight module comprises: an LED matrix, a feedback network and a driving device; the LED matrix comprises two or more current regions, and the same current region comprises at least one light-emitting unit group; each light-emitting unit group comprises at least one light-emitting unit; the feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current region; The driving device is suitable for providing the light-emitting units in different current regions with control channel currents matching the current regions in which they are located, so as to drive the light-emitting units in different current regions to emit light in a time-sharing manner within the same frame; The voltage control method comprises: In one frame, the voltage at the voltage feedback node of the feedback network corresponding to the light emitting unit in each current region is collected when the light emitting unit in each current region emits light, and based on the collected voltage, an operating voltage matching the collected voltage is provided to the light emitting unit in each current region.

2. The voltage control method of the backlight module according to claim 1, characterized in that: The step of providing a light-emitting unit in each current region with a working voltage matching the collected voltage based on the collected voltage includes: comparing the collected voltage with a preset reference voltage; Based on the difference between the collected voltage and the preset reference voltage, an operating voltage is provided for the light-emitting unit in the current current region, so that the collected voltage is equal to the preset reference voltage.

3. The voltage control method of the backlight module according to claim 2, characterized in that: The LED matrix includes a first current region and a second current region. The control channel current of the light-emitting unit in the first current region is a first current. The control channel current of the light-emitting unit in the second current region is a second current. The first current is greater than the second current.

4. The voltage control method of the backlight module according to claim 3, characterized in that: The providing a working voltage for the light-emitting unit in the current current region based on the difference between the collected voltage and the preset reference voltage includes: When the collected voltage is less than the preset reference voltage, a first operating voltage is provided to the light-emitting unit in the current current region, wherein the first operating voltage is greater than the preset reference voltage; When the collected voltage is greater than the preset reference voltage, a second operating voltage is provided to the light-emitting unit in the current current region, and the second operating voltage is less than the first operating voltage.

5. The voltage control method of the backlight module according to claim 3, characterized in that: The first current region is an edge region of the backlight module; and the second current region is a non-edge region of the backlight module.

6. A power management device for a backlight module, characterized in that: The backlight module comprises: an LED matrix, a feedback network and a driving device; the LED matrix comprises two or more current regions, and the same current region comprises at least one light-emitting unit group; each light-emitting unit group comprises at least one light-emitting unit; the feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current region; The power management device comprises: A collection unit, adapted to collect, within one frame, the voltage at the voltage feedback node of the feedback network corresponding to the light-emitting unit in each current region emitting light; The voltage control unit is adapted to provide the light-emitting units in each current region with an operating voltage matching the collected voltage based on the collected voltage.

7. The power management device according to claim 6, characterized in that: The voltage control unit comprises: A comparison subunit, adapted to compare the collected voltage with a preset reference voltage; The power supply subunit is adapted to provide an operating voltage for the light emitting unit in the current current region based on the difference between the collected voltage and the preset reference voltage, so that the collected voltage is equal to the preset reference voltage.

8. The power management device according to claim 7, wherein: The LED matrix includes a first current region and a second current region. The control channel current of the light-emitting unit in the first current region is a first current. The control channel current of the light-emitting unit in the second current region is a second current. The first current is greater than the second current.

9. The power management device according to claim 8, characterized in that: The power supply unit is suitable for providing a first operating voltage for the light-emitting unit in the current current region when the collected voltage is less than the preset reference voltage, and the first operating voltage is greater than the preset reference voltage; and when the collected voltage is greater than the preset reference voltage, providing a second operating voltage for the light-emitting unit in the current current region, and the second operating voltage is less than the first operating voltage.

10. The power management device according to claim 8, wherein: The first current region is an edge region of the backlight module; and the second current region is a non-edge region of the backlight module.

11. A method for driving a backlight module, characterized in that: The backlight module comprises: an LED matrix, a feedback network, a micro control unit, and a power management device for the backlight module according to any one of claims 6 to 10; The LED matrix includes more than two current regions, and the same current region includes at least one light-emitting unit group; each of the light-emitting unit groups includes at least one light-emitting unit; The feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current range; The power management device is suitable for providing a working voltage matching the collected voltage to the light-emitting units in each current region within a frame; The micro control unit is connected to the feedback network and is used to change the voltage of the voltage feedback node of the feedback network before switching the working voltage of the LED matrix; The driving method comprises: Before the voltage of the voltage feedback node of the feedback network changes, turning off the current of all control channels; And after the voltage change of the voltage feedback node of the feedback network reaches a preset time length, the light-emitting units in different current regions are provided with control channel currents matching the current regions, so as to drive the light-emitting units in different current regions to emit light in time-sharing within the same frame.

12. The driving method of the backlight module according to claim 11, wherein: The preset duration is related to the fluctuation duration of the working voltage provided by the power management device.

13. The driving method of the backlight module according to claim 12, wherein: The preset duration ranges from 160us to 240us.

14. The driving method of the backlight module according to claim 11, wherein: The light-emitting units in the same light-emitting unit group are connected to the working voltage output terminal of the power management device through the same switch tube; The method provides the light-emitting units in different current regions with control channel currents matching the current regions in which they are located, so as to drive the light-emitting units in different current regions to emit light in a time-sharing manner in the same frame, including: The switch tubes corresponding to different light-emitting unit groups in the same current region are activated in sequence, and the light-emitting units connected to the activated switch tubes are provided with control channel currents matching the current region; within one frame, the light-emitting unit groups in the same current region emit light simultaneously.

15. The driving method of the backlight module according to claim 11, wherein: The micro control unit includes: a micro controller, a micro switch, and a micro resistor connected in parallel with the micro switch; the micro resistor is connected to the feedback network; the micro switch is suitable for opening or closing under the control of the micro controller to change the voltage of the voltage feedback node of the feedback network.

16. A driving device for a backlight module, characterized in that: The backlight module comprises: an LED matrix, a feedback network, a micro control unit, and a power management device for the backlight module according to any one of claims 6 to 10; The LED matrix includes more than two current regions, and the same current region includes at least one light-emitting unit group; each of the light-emitting unit groups includes at least one light-emitting unit; The feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current range; The power management device is suitable for providing a working voltage matching the collected voltage to the light-emitting units in each current region within a frame; The micro control unit is connected to the feedback network and is used to change the voltage of the voltage feedback node of the feedback network before switching the working voltage of the LED matrix; The driving device comprises: a channel current control unit adapted to shut down the currents of all control channels before the voltage of the voltage feedback node of the feedback network changes; A timing unit, adapted to time the duration of a change in voltage of a voltage feedback node of the feedback network; The channel current control unit is also suitable for providing the light-emitting units in different current regions with a control channel current matching the current region after the voltage change at the voltage feedback node of the feedback network reaches a preset time length, so as to drive the light-emitting units in different current regions to emit light in time-sharing within the same frame.

17. A backlight module, characterized in that: include: LED matrix, feedback network, power management device of backlight module according to any one of claims 6 to 10, and driving device of backlight module according to claim 16; wherein: The LED matrix includes more than two current regions, and the same current region includes at least one light-emitting unit group; each of the light-emitting unit groups includes at least one light-emitting unit; The feedback network is connected to the voltage collection end of the LED matrix; the feedback network has a voltage feedback node, and the voltage at the voltage feedback node is used to feedback the actual required voltage of the light-emitting unit in the current current range; The power management device is suitable for providing a working voltage matching the collected voltage to the light-emitting units in each current region within a frame; The driving device is suitable for providing the light-emitting units in different current regions with control channel currents matching the current regions in which they are located, so as to drive the light-emitting units in different current regions to emit light in a time-sharing manner in the same frame.

18. The backlight module according to claim 17, wherein: The backlight module further includes: a micro control unit, The micro control unit is connected to the feedback network and is used to change the voltage of the voltage feedback node of the feedback network before switching the working voltage of the LED matrix; The driving device is suitable for turning off the current of all control channels before the voltage of the voltage feedback node of the feedback network changes; and providing control channel currents matching the current regions for the light-emitting units in different current regions after the voltage change of the voltage feedback node of the feedback network reaches a preset time length, so as to drive the light-emitting units in different current regions to emit light in time-sharing within the same frame.

19. The backlight module according to claim 18, wherein: The micro control unit includes: a micro controller, a micro switch, and a micro resistor connected in parallel with the micro switch; the micro resistor is connected to the feedback network; the micro switch is suitable for opening or closing under the control of the micro controller to change the voltage of the voltage feedback node of the feedback network.

20. The backlight module according to claim 19, wherein: The feedback network includes: a first feedback resistor and a second feedback resistor connected in series; the other end of the first feedback resistor is connected to the voltage collection end of the LED matrix; and the other end of the second feedback resistor is connected to the micro-control resistor.

21. A liquid crystal display device, characterized in that: The backlight module comprises any one of claims 17 to 20.

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