Controller for controlling a light source module

Abstract

The present invention provides a controller for controlling a light source module. The light source module includes a first light emitting diode array and a second light emitting diode array. The controller includes a first driving port, a second driving port, and a plurality of current sensing ports. The first driving port is coupled to a first switch. The second driving port is coupled to a second switch. The plurality of current sensing ports are configured to sense the current of each light emitting diode string in the first light emitting diode array and the current of each light emitting diode string in the second light emitting diode array, respectively. The controller is configured to turn on the first switch through the first driving port in a first discrete time slot sequence to transfer electrical energy from a power converter to the first light emitting diode array; and is further configured to turn on the second switch through the second driving port in a second discrete time slot sequence to transfer electrical energy from the power converter to the second light emitting diode array, wherein the first discrete time slot sequence and the second discrete time slot sequence are mutually exclusive.

Description

Technical Field

[0001] The present invention relates to the technical field of controllers, and more particularly to a controller for controlling a light source module. Background Art

[0002] In a Light-Emitting Diode (LED) display system, such as a Liquid Crystal Display (LCD) television, a controller is typically used to control the power of multiple LED strings for backlighting. Since the controller has only a specified number of control pins, the controller can only control a limited number of LED strings. To control a larger number of LED strings, a larger number of controllers are required, which also increases the cost of the system. Summary of the Invention

[0003] The present invention provides a controller for controlling a light source module. The light source module includes a first light-emitting diode array and a second light-emitting diode array. The first light-emitting diode array includes a first group of light-emitting diode strings, and the second light-emitting diode array includes a second group of light-emitting diode strings. The controller includes a first drive port, a second drive port, and a plurality of current sensing ports. The first drive port is coupled to a first switch, where the first switch is coupled between a power converter and the first light-emitting diode array; the second drive port is coupled to a second switch, where the second switch is coupled between the power converter and the second light-emitting diode array; and the plurality of current sensing ports are coupled to the first light-emitting diode array and the second light-emitting diode array for sensing the current of each light-emitting diode string in the first light-emitting diode array and the current of each light-emitting diode string in the second light-emitting diode array, respectively; where the anodes of the first group of light-emitting diode strings are connected to a first common node, where the first common node is connected to the first switch, where the anodes of the second group of light-emitting diode strings are connected to a second common node, where the second common node is connected to the second switch, where the cathodes of the first light-emitting diode strings in the first light-emitting diode array and the cathodes of the first light-emitting diode strings in the second light-emitting diode array are both connected to a third common node, where the third common node is connected to a first current sensing port among the plurality of current sensing ports, and where the controller is configured to turn on the first switch through the first drive port in a first discrete time slot sequence to transfer electrical energy from the power converter to the first light-emitting diode array; and to turn on the second switch through the second drive port in a second discrete time slot sequence to transfer electrical energy from the power converter to the second light-emitting diode array; where the first discrete time slot sequence and the second discrete time slot sequence are mutually exclusive.

[0004] The present invention also provides a controller. The controller is coupled to a power supply and is configured to control a light source module including a first light-emitting diode (LED) array and a second LED array. The first LED array includes a first group of LED strings, and the second LED array includes a second group of LED strings. The controller includes a decoding module and a residual image elimination module. The decoding module is configured to receive a timing signal from a timing controller and generate switching signals to control a first switch and a second switch according to the timing signal, where the first switch is coupled between a power converter and the first LED array, and the second switch is coupled between the power converter and the second LED array; and the residual image elimination module is coupled to the decoding module and is configured to adjust the voltage across each LED string in the first LED array to make the voltage across each LED string in the first LED array lower than a threshold, and is further configured to adjust the voltage across each LED string in the second LED array to make the voltage across each LED string in the second LED array lower than the threshold. Wherein, the decoding module is configured to turn on the first switch in a first discrete time slot sequence and is further configured to turn on the second switch in a second discrete time slot sequence, and the first discrete time slot sequence and the second discrete time slot sequence are mutually exclusive.

[0005] As described above, the present invention discloses a controller for controlling a light source module. When a certain LED string in the light source module should not be lit, the controller adjusts the voltage across the LED string to make it lower than the conduction threshold. Therefore, the LED string will not be inadvertently lit, thereby eliminating the phenomenon of residual images on the display device. Brief Description of the Drawings

[0006] The objects, specific structural features and advantages of the present invention can be further understood through the description of some embodiments of the present invention in conjunction with their accompanying drawings.

[0007] Figure 1 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0008] Figure 2 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0009] Figure 3 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0010] Figure 4 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0011] Figure 5 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0012] Figure 6 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0013] Figure 7 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0014] Figure 8 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0015] Figure 9 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0016] Figure 10 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0017] Figure 11 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0018] Figure 12 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0019] Figure 13 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0020] Figure 14 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0021] Figure 15 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0022] Figure 16 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0023] Figure 17 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0024] Figure 18 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0025] Figure 19 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

[0026] Figure 20Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0027] Figure 21 Shown is a voltage regulation unit in a controller according to an embodiment of the present invention;

[0028] Figure 22 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention;

[0029] Figure 23 Shown is a timing diagram of a controller for controlling a light source module according to an embodiment of the present invention; and

[0030] Figure 24 Shown is a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention. Detailed Description of the Invention

[0031] Embodiments of the present invention will be described in detail below. Although the present invention is described and illustrated by these embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, the present invention covers all alternatives, variations, and equivalents within the spirit and scope of the invention defined by the appended claims.

[0032] In addition, for a better illustration of the present invention, numerous specific details are given in the following detailed description. Those skilled in the art will understand that the present invention can be implemented without these specific details. In some other instances, well-known methods, processes, elements, and circuits are not described in detail to highlight the gist of the present invention.

[0033] Figure 1 Shown is a light source driving circuit 100 including a controller 180 for controlling a light source module according to an embodiment of the present invention. In Figure 1 the example, the light source module includes 4 light-emitting diode (LED) arrays A1, A2, A3, and A4. Each LED array includes a plurality of (e.g., 8) LED strings. This embodiment can be used as a basis for the discussion below, but this embodiment includes, but is not limited to, 4 LED arrays and / or 8 LED strings in each array.

[0034] The controller 180 receives electrical energy from the power converter 120. The power converter 120 is coupled between the controller 180 and the power supply 110. The controller 180 includes a power input port PWIN, a feedback port FBOUT, a plurality of power output ports PWO1 - PWO4, and a plurality of current sensing ports ISEN1 - ISEN8. The number of power output ports is equal to the number of LED arrays. The number of current sensing ports is equal to the number of LED strings in each LED array. The controller 180 includes a switching module 130, a feedback control module 140, a current regulation module 150, and a decoding module 160.

[0035] The power input port PWIN is coupled to the power supply 110 through the power converter 120 and is used to receive electrical energy from the power converter 120. The power output ports PWO1 - PWO4 are respectively and correspondingly coupled to the LED arrays A1 - A4. The controller 180 is used to transfer electrical energy to the LED arrays A1 - A4 through the power output ports PWO1 - PWO4 in the first, second, third, and fourth discrete time slot sequences respectively. The first, second, third, and fourth discrete time slot sequences do not overlap with each other, that is to say, they have no overlap in time.

[0036] Specifically, the switching module 130 includes a plurality of switches SW1 - SW4. The plurality of switches SW1 - SW4 are respectively coupled between the power input port PWIN and the corresponding power output port. For example, the first switch SW1 is coupled between the power input port PWIN and the first power output port PWO1, and the second switch SW2 is coupled between the power input port PWIN and the second power output port PWO2. Please refer to Figure 3 , the controller 180 is used to turn on the first switch SW1 in the first discrete time slot sequence T11, T12, T13, turn on the second switch SW2 in the second discrete time slot sequence T21, T22, T23, turn on the third switch SW3 in the third discrete time slot sequence T31, T32, T33, and turn on the fourth switch SW4 in the fourth discrete time slot sequence T41, T42, T43. As Figure 3 shown, the first, second, third, and fourth discrete time slot sequences do not overlap with each other (that is to say, they do not occur simultaneously, they have no overlap in time), and are staggered with each other.

[0037] Please continue to refer to Figure 1 , the current sensing ports ISEN1 - ISEN8 are respectively and correspondingly coupled to the LED arrays A1 - A4 and are used to sense the current magnitude of each LED string in the LED arrays A1 - A4, and the method will be introduced below. The current regulation module 150 is coupled to the LED arrays A1 - A4 through the current sensing ports ISEN1 - ISEN8 and is used to linearly regulate the current of each LED string in the LED arrays A1 - A4. The specific situation will be inFigure 2 It is introduced in detail in

[0038] Please continue to refer to Figure 1 , the feedback control module 140 is used to generate a feedback signal FB according to the power demand of the light source module to control the power converter 120, so that the electric energy from the power converter 120 can meet the power demand of the light source module. Through the feedback port FBOUT, the feedback signal FB is provided to the power converter 120. The feedback control module 140 is coupled to the current sensing ports ISEN1 - ISEN8 and generates a feedback signal FB according to the voltages on the current sensing ports ISEN1 - ISEN8. The voltages on the current sensing ports ISEN1 - ISEN8 can indicate the power demand of the light source module. Specifically, the feedback control module 140 selects the minimum voltage among the voltages on the current sensing ports ISEN1 - ISEN8 and compares the minimum voltage with a preset voltage range to generate the feedback signal FB. Under the control of the feedback signal FB, the power converter 120 increases or decreases the electric energy so that the minimum voltage is within the preset voltage range.

[0039] The decoding module 160 is used to receive timing signals from the timing controller 190 (such as, a micro control unit) and generate switching signals to control the switches SW1 - SW4 in the switching module 130. The decoding module 160 is also used to generate a plurality of control signals to control the current regulation module 150. Accordingly, a plurality of current regulation units (such as Figure 2 shown) can be individually enabled or disabled according to the corresponding control signals. For example, the decoding module 160 can communicate with the timing controller 190 through a Serial Peripheral Interface (SPI).

[0040] The LED arrays A1 - A4 are configured to receive electric energy from the power output ports PWO1 - PWO4 respectively and share the current sensing ports ISEN1 - ISEN8. Specifically, the anodes of the LED strings in the first LED array A1 are connected to the common node N1, and the common node N1 is connected to the first power output port PWO1. The anodes of the LED strings in the second LED array A2 are connected to the common node N2, and the common node N2 is connected to the second power output port PWO2. The anodes of the LED strings in the third LED array A3 are connected to the common node N3, and the common node N3 is connected to the third power output port PWO3. The anodes of the LED strings in the fourth LED array A4 are connected to the common node N4, and the common node N4 is connected to the fourth power output port PWO4.

[0041] On the other hand, the cathodes of the first LED strings in the first LED array A1, the cathodes of the first LED strings in the second LED array A2, the cathodes of the first LED strings in the third LED array A3, and the cathodes of the first LED strings in the fourth LED array A4 are all connected to the first common node NC1. The first common node NC1 is connected to the current sensing port ISEN1. Therefore, the current sensing port ISEN1 senses the current on the first LED string in each LED array. Similarly, the cathodes of the second LED strings in each LED array are connected to the second common node NC2 (not marked in the figure). The second common node NC2 is connected to the current sensing port ISEN2 (not marked in the figure). By analogy, the cathodes of the last (e.g., the 8th) LED strings in each LED array are connected to the corresponding (e.g., the 8th) common node NC8. The common node NC8 is connected to the current sensing port ISEN8.

[0042] During the operation of the circuit, if the switch SW1 is turned on, the current flows through the first power output port PWO1, the common node N1, reaches the first LED array A1, and then returns to the controller 180 through the common nodes NC1-NC8 and the current sensing ports ISEN1-ISEN8. If the switch SW2 is turned on, the current flows through the second power output port PWO2, the common node N2, reaches the second LED array A2, and then returns to the controller 180 through the common nodes NC1-NC8 and the current sensing ports ISEN1-ISEN8. The configuration of the controller 180 and the structure of the circuit 100 enable the LED arrays A1-A4 to share the same set of current sensing ports ISEN1-ISEN8.

[0043] Figure 2 Shown is a light source driving circuit 200 including a controller 180 for controlling a light source module according to an embodiment of the present invention. Figure 2 A detailed view of the internal structure of the controller 180 is shown. The controller 180 includes a switch module 130, a feedback control module 140, a current regulation module 150, and a decoding module 160.

[0044] The current regulation module 150 includes a plurality of current regulation units 230_1-230_8. The plurality of current regulation units 230_1-230_8 are respectively coupled to the current sensing ports ISEN1-ISEN8 and are used to linearly regulate the current of each LED string in the LED arrays A1-A4. Each current regulation unit is independently enabled and disabled according to the corresponding control signal among the control signals PWM1-PWM8. The control signals PWM1-PWM8 can be Pulse Width Modulation (PWM) signals.

[0045] Specifically, the current regulation units 230_1 - 230_8 respectively include amplifiers 290_1 - 290_8. The amplifiers 290_1 - 290_8 are respectively coupled to switches Q1 - Q8. The switches Q1 - Q8 are respectively coupled in series with the corresponding LED strings. Each current regulation unit has a similar structure. Taking the current regulation unit 230_1 as an example. The non-inverting input terminal of the amplifier 290_1 receives a reference signal ADJ1 indicating the target current. The inverting input terminal of the amplifier 290_1 receives an induction signal IS1 indicating the magnitude of the current flowing through the corresponding LED string. The amplifier 290_1 compares the reference signal ADJ1 with the induction signal IS1 to generate an error signal EA1, and linearly controls the switch Q1 using the error signal EA1 to regulate the current of the corresponding LED string so that the current is at the target current. The switch Q1 being linearly controlled means that the switch Q1 is not fully turned on or fully turned off, but can be partially turned on so that the magnitude of the current flowing through the switch Q1 can be continuously (non-discretely), gradually regulated.

[0046] The amplifier 290_1 is controlled by a control signal PWM1. If the control signal PWM1 is in the first state (e.g., logic high), the amplifier 290_1 is enabled, and at the same time the corresponding LED string is turned on and regulated as described above. If the control signal PWM1 is in the second state (e.g., logic low), the amplifier 290_1 is disabled, and at the same time the corresponding LED string is turned off.

[0047] In one embodiment, the decoding module 160 includes an SPI decoder 210, a PWM generator 220, a digital-analog convertor (DAC) 240, and a reference signal selection unit 250. The SPI decoder 210 receives a timing signal from a timing controller (not shown in the figure) and decodes the timing signal. The PWM generator 220 is coupled to the SPI decoder 210 and generates control signals PWM1 - PWM8 according to the timing signal. The DAC 240 is coupled to the SPI decoder 210 and generates reference signals ADJ1 - ADJ8. The reference signal selection unit 250 either selects the reference signals ADJ1 - ADJ8 or selects the system reference signal SYS_REF, and provides the selected signal (e.g., ADJ1 - ADJ8 or SYS_REF) to the corresponding amplifiers 290_1 - 290_8. The system reference signal SYS_REF is also generated from the SPI decoder 210. In other words, either the in-phase input terminal of amplifier 290_1 receives the reference signal ADJ1, the in-phase input terminal of amplifier 290_2 receives the reference signal ADJ2, etc., or the in-phase input terminals of amplifiers 290_1 - 290_8 all receive the system reference signal SYS_REF. Further, the decoding module 160 processes the timing signal and provides a switching signal to the switching module 130. The switching module 130 controls switches SW1 - SW4 using the switching signal to turn on switches SW1 - SW4 in four non-overlapping discrete time slot sequences.

[0048] As described above, the present invention includes a controller for controlling a light source module. The controller is used to selectively transfer electrical energy to a plurality of LED arrays (e.g., first to one LED array, then to another LED array, and so on, with only one LED array at a time), and is also used to adjust the current of each LED string in the plurality of LED arrays. The controller enables the plurality of LED arrays to share the same set of current sensing ports in the controller. Advantageously, the plurality of LED arrays can be controlled by a single controller, thereby reducing the cost of the system. More importantly, each LED string in the plurality of LED arrays can be individually adjusted or disabled, thereby allowing flexible and fine dimming in the display system.

[0049] Figure 4 Shown is a light source driving circuit 400 including a controller 480 for controlling a light source module according to an embodiment of the present invention. Elements with the same reference numerals as Figure 1 have similar functions. Figure 4 will be described in conjunction with Figure 1 introduced. Figure 4 The shown embodiment is different from the embodiment shown in Figure 1 mainly in that Figure 1 the switching module 130 inFigure 4 The switch module 130 in Figure 4 is located outside the controller 480. The controller 480 is respectively coupled to switches SW1 - SW4 through a plurality of drive ports DRVP1 - DRVP4. Switch SW1 is coupled between the power converter 120 and the first LED array A1. Switch SW2 is coupled between the power converter 120 and the second LED array A2. Switch SW3 is coupled between the power converter 120 and the third LED array A3. Switch SW4 is coupled between the power converter 120 and the fourth LED array A4. A plurality of current sensing ports ISEN1 - ISEN8 are coupled to the plurality of LED arrays A1 - A4 for sensing the current magnitude of each LED string in the LED arrays A1 - A4. The anodes of each LED string in the first LED array A1 are connected to a common node N1, and the common node N1 is connected to switch SW1. The anodes of each LED string in the second LED array A2 are connected to a common node N2, and the common node N2 is connected to switch SW2. The anodes of each LED string in the third LED array A3 are connected to a common node N3, and the common node N3 is connected to switch SW3. The anodes of each LED string in the fourth LED array A4 are connected to a common node N4, and the common node N4 is connected to switch SW4. The cathodes of the first LED string in the first LED array A1, the cathodes of the first LED string in the second LED array A2, the cathodes of the first LED string in the third LED array A3, and the cathodes of the first LED string in the fourth LED array A4 are all connected to a first common node NC1. The first common node NC1 is connected to the current sensing port ISEN1. Therefore, the current sensing port ISEN1 senses the current on the first LED string in each LED array. Similarly, the cathodes of the second LED string in each LED array are connected to a second common node NC2 (not marked in the figure). The second common node NC2 is connected to the current sensing port ISEN2 (not marked in the figure). And so on, the cathodes of the last (e.g., the 8th) LED string in each LED array are connected to the corresponding (e.g., the 8th) common node NC8. The common node NC8 is connected to the current sensing port ISEN8.

[0050] The controller 480 is configured to turn on the first switch SW1 through the first driving port DRVP1 in the first discrete time slot sequence T11, T12, T13 to transfer electrical energy from the power converter 120 to the first LED array A1. The controller 480 is further configured to turn on the second switch SW2 through the second driving port DRVP2 in the second discrete time slot sequence T21, T22, T23 to transfer electrical energy from the power converter 120 to the second LED array A2. The controller 480 is further configured to turn on the third switch SW3 through the third driving port DRVP3 in the third discrete time slot sequence T31, T32, T33 to transfer electrical energy from the power converter 120 to the third LED array A3. The controller 480 is further configured to turn on the fourth switch SW4 through the fourth driving port DRVP4 in the fourth discrete time slot sequence T41, T42, T43 to transfer electrical energy from the power converter 120 to the fourth LED array A4. As Figure 3 shown, the first, second, third, and fourth discrete time slot sequences do not overlap with each other and are interleaved. Specifically, the decoding module 160 is configured to receive a timing signal from the timing controller 190 and generate switching signals to control the plurality of switches SW1-SW4 in the manner described above.

[0051] Since the switches SW1-SW4 are typically implemented by metal oxide semiconductor (MOS) transistors that include parasitic capacitance, when turning off an LED string (e.g., the first LED string in the first LED array A1) by turning off the switch SW1, if the switch Q1 (in Figure 2 the current regulation module 150 shown) is in the on state, a spike current flowing through the parasitic capacitance of the switch SW1 and flowing to the ground through the switch Q1 will be generated. Such a spike current can briefly light up the first LED string. If the light source driving circuit 400 is used for backlight driving of a display device such as a television or a computer monitor, this will generate an undesired residual image on the screen of the display device. To solve this problem, various embodiments according to the present invention are disclosed in Figures 5 to 24 this document.

[0052] Figure 5 Shown is a light source driving circuit 500 according to an embodiment of the present invention, including a controller 580 for controlling a light source module. Elements having the same reference numerals as Figure 4 those in this document have similar functions. In Figure 5In the illustrated embodiment, the controller 580 includes a plurality of discharge ports DIS1-DIS4, and each discharge port is coupled to the anodes of the LED strings in the corresponding LED array. For example, the discharge port DIS1 is coupled to the anodes of the LED strings in the first LED array A1 (e.g., the common node N1). The discharge port DIS2 is coupled to the anodes of the LED strings in the second LED array A2 (e.g., the common node N2), and so on. The controller 580 includes a residual image elimination module 501. The residual image elimination module 501 is coupled to the decoding module 160 and is used to adjust the voltage on each LED string in each LED array to be lower than a threshold (the threshold is referred to as the turn-on threshold). The turn-on threshold is set such that no LED string is turned on due to a spike current. The residual image elimination module 501 includes a plurality of voltage adjustment units, such as the voltage adjustment units 511-514 as an example. The number of voltage adjustment units can be determined according to the number of LED arrays and the number of LED strings in each LED array. Each of the voltage adjustment units 511-514 can be individually enabled or disabled by a corresponding enable signal. For example, the voltage adjustment unit 511 can be controlled by the enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (as shown in Figure 5 ). The voltage adjustment units 511-514 are respectively coupled to the plurality of discharge ports DIS1-DIS4. Specifically, the voltage adjustment unit 511 is coupled to the first discharge port DIS1 and is used to reduce the voltage on the anode of the first LED string in the first LED array A1 to adjust the voltage on the first LED string in the first LED array A1 to be lower than the threshold.

[0053] Figure 6 Shown is the voltage adjustment unit 511 in the controller 580 according to an embodiment of the present invention. In Figure 6 In the illustrated embodiment, the voltage adjustment unit 511 includes an amplifier 601 and a discharge switch 602. The discharge switch 602 is coupled between the discharge port DIS1 and the ground. The non-inverting input terminal of the amplifier 601 receives the first voltage signal V1, the inverting input terminal of the amplifier 601 is coupled to the discharge port DIS1, and the output terminal of the amplifier 601 is coupled to the discharge switch 602. When enabled by the enable signal EN1, the amplifier 601 adjusts the voltage on the anode of the first LED string in the first LED array A1 to follow the first voltage signal V1, thereby reducing the voltage on the first LED string in the first LED array A1 to be lower than the turn-on threshold.

[0054] Figure 7 Shown is the voltage adjustment unit 511 in the controller 580 according to an embodiment of the present invention. In Figure 7In the illustrated embodiment, the voltage regulation unit 511 includes a comparator 701 and a discharge switch 702. The discharge switch 702 is coupled between the discharge port DIS1 and the ground. The non-inverting input terminal of the comparator 701 receives the second voltage signal V2, the inverting input terminal of the comparator 701 is coupled to the discharge port DIS1, and the output terminal of the comparator 701 is coupled to the discharge switch 702. When enabled by the enable signal EN1, the comparator 701 compares the voltage on the anode of the first LED string in the first LED array A1 with the second voltage signal V2. If the voltage on the anode of the first LED string in the first LED array A1 is greater than the second voltage signal V2, the comparator 701 turns on the discharge switch 702 to conduct a discharge current flowing from the anode of the first LED string in the first LED array A1 through the discharge switch 702 to the ground, thereby reducing the voltage on the first LED string in the first LED array A1 to make it lower than the conduction threshold.

[0055] Figure 8 Shown is the voltage regulation unit 511 in the controller 580 according to an embodiment of the present invention. In Figure 8 In the illustrated embodiment, the voltage regulation unit 511 includes a discharge switch 802. The discharge switch 802 is coupled between the discharge port DIS1 and the ground. When turned on by the enable signal EN1, the discharge switch 802 conducts a discharge current flowing from the anode of the first LED string in the first LED array A1 to the ground, thereby reducing the voltage on the first LED string in the first LED array A1 to make it lower than the conduction threshold.

[0056] Figure 9 Shown is the voltage regulation unit 511 in the controller 580 according to an embodiment of the present invention. In Figure 9 In the illustrated embodiment, the voltage regulation unit 511 includes a current mirror 901. The first branch of the current mirror 901 is coupled between the discharge port DIS1 and the ground, and the second branch is coupled between the current source 902 and the ground. A switch 903 is coupled to the current mirror 901 for enabling or disabling the current mirror 901 according to the enable signal EN1. When enabled, the current mirror 901 conducts a discharge current flowing from the anode of the first LED string in the first LED array A1 through the first branch to the ground, thereby reducing the voltage on the first LED string in the first LED array A1 to make it lower than the conduction threshold.

[0057] Continue to refer to Figure 5 , according to different timing schemes, the voltage regulation unit 511 can be enabled when the enable signal EN1 is at the first level (e.g., logic high), or disabled when the enable signal EN1 is at the second level (e.g., logic low). In one embodiment, the voltage regulation unit 511 can be always enabled. In another embodiment, as Figure 10As shown, when the first switch SW1 is turned off, the voltage regulation unit 511 can be enabled. In another embodiment, as Figure 11 shown, the voltage regulation unit 511 can be enabled during the time interval sequence BBM. The time interval sequence BBM is the interval between four discrete time slot sequences in which the switches SW1 - SW4 are mutually exclusive and turned on. In other words, during each interval in the time interval sequence BBM, none of the switches SW1 - SW4 is turned on, while the voltage regulation unit 511 is enabled.

[0058] Figure 12 Shown is a light source driving circuit 1200 including a controller 1280 for controlling a light source module according to an embodiment of the present invention. Elements with the same reference numerals as Figure 4 have similar functions. The controller 1280 includes a power supply port VLEDIN coupled to a power converter 120. The controller 1280 also includes a residual image elimination module 1201 coupled to a decoding module 160. The residual image elimination module 1201 is used to adjust the voltage on each LED string in each LED array to be lower than the conduction threshold. The conduction threshold is set such that no LED string is turned on due to a spike current. The residual image elimination module 1201 includes a plurality of voltage regulation units, such as the voltage regulation units 1211 - 1214 by way of example. The number of voltage regulation units can be determined according to the number of LED arrays and the number of LED strings in each LED array. Each of the voltage regulation units 1211 - 1214 can be individually enabled or disabled through corresponding enable signals. For example, the voltage regulation unit 1211 can be controlled by an enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (shown in Figure 5 ). The voltage regulation units 1211 - 1214 are coupled to the power supply port VLEDIN and a plurality of current sensing ports ISEN1 - ISEN8. Specifically, the voltage regulation unit 1211 is coupled to the power supply port VLEDIN and the current sensing port ISEN1, and is used to increase the voltage on the cathode of the first LED string in the first LED array A1 to adjust the voltage on the first LED string in the first LED array A1 to be lower than the threshold.

[0059] Figure 13 Shown is the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In Figure 13In the illustrated embodiment, the voltage regulation unit 1211 includes an amplifier 1301 and a charging switch 1302. The charging switch 1302 is coupled between the power supply port VLEDIN and the current sensing port ISEN1. The non-inverting input terminal of the amplifier 1301 receives a third voltage signal V3. The inverting input terminal of the amplifier 1301 is coupled to the current sensing port ISEN1. The output terminal of the amplifier 1301 is coupled to the charging switch 1302. When enabled by an enable signal EN1, the amplifier 1301 regulates the voltage on the cathode of the first LED string in the first LED array A1 to follow the third voltage signal V3, thereby reducing the voltage across the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0060] Figure 14 Shown is the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In Figure 14 In the illustrated embodiment, the voltage regulation unit 1211 includes a comparator 1401 and a charging switch 1402. The charging switch 1402 is coupled between the power supply port VLEDIN and the current sensing port ISEN1. The non-inverting input terminal of the comparator 1401 receives a fourth voltage signal V4. The inverting input terminal of the comparator 1401 is coupled to the current sensing port ISEN1. The output terminal of the comparator 1401 is coupled to the charging switch 1402. When enabled by an enable signal EN1, the comparator 1401 compares the voltage on the cathode of the first LED string in the first LED array A1 with the fourth voltage signal V4. If the voltage on the cathode of the first LED string in the first LED array A1 is lower than the fourth voltage signal V4, the comparator 701 turns on the charging switch 1402 to conduct a charging current flowing from the power supply port VLEDIN through the charging switch 1402 to the cathode of the first LED string in the first LED array A1, thereby reducing the voltage across the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0061] Figure 15 Shown is the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In Figure 15 In the illustrated embodiment, the voltage regulation unit 1211 includes a charging switch 1502. The charging switch 1502 is coupled between the power supply port VLEDIN and the current sensing port ISEN1. When turned on by an enable signal EN1, the charging switch 1502 conducts a charging current flowing from the power supply port VLEDIN to the cathode of the first LED string in the first LED array A1, thereby reducing the voltage across the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0062] Figure 16 Shown is the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In Figure 16In the illustrated embodiment, the voltage regulation unit 1211 includes a current mirror 1601. The first branch of the current mirror 1601 is coupled between the power supply port VLEDIN and the current sensing port ISEN1, and the second branch of the current mirror 1601 is coupled between the power supply port VLEDIN and the current source 1602. A switch 1603 is coupled to the current mirror 1601 for enabling or disabling the current mirror 1601 according to the enable signal EN1. When enabled, the current mirror 1601 conducts a charging current flowing from the power supply port VLEDIN through the first branch to the cathode of the first LED string in the first LED array A1, thereby reducing the voltage across the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0063] Continuing to refer to Figure 12 , according to different timing schemes, the voltage regulation unit 1211 can be enabled when the enable signal EN1 is at a first level (e.g., logic high), or the voltage regulation unit 1211 can be disabled when the enable signal EN1 is at a second level (e.g., logic low). In one embodiment, as Figure 17 illustrated, the voltage regulation unit 1211 can be enabled in the time interval sequence BBM. The time interval sequence BBM is the interval between four discrete time slots in which the switches SW1 - SW4 are mutually exclusive and turned on. In other words, in each interval of the time interval sequence BBM, any one of the switches SW1 - SW4 is not turned on while the voltage regulation unit 1211 is enabled. In another embodiment, as Figure 18 illustrated, the voltage regulation unit 1211 can be enabled in the time interval sequence BBM, and if the corresponding control signal PWM1 (as Figure 2 illustrated) is in a second state (e.g., logic low), the voltage regulation unit 1211 can also be enabled.

[0064] Figure 19 Shown is a light source driving circuit 1900 including a controller 1980 for controlling a light source module according to an embodiment of the present invention. Elements having the same reference numerals as Figure 4 have similar functions. In Figure 19In the illustrated embodiment, the controller 1980 includes a plurality of discharge ports DIS1 - DIS4, and each discharge port is coupled to the anodes of the LED strings in the corresponding LED array. For example, the discharge port DIS1 is coupled to the anodes of the LED strings in the first LED array A1 (e.g., the common node N1). The discharge port DIS2 is coupled to the anodes of the LED strings in the second LED array A2 (e.g., the common node N2), and so on. The controller 1980 includes a residual image elimination module 1901. The residual image elimination module 1901 is coupled to the decoding module 160 and is used to adjust the voltage on each LED string in each LED array to be lower than the conduction threshold. The conduction threshold is set such that no LED string is turned on due to the spike current. The residual image elimination module 1901 includes a plurality of voltage adjustment units, such as the voltage adjustment units 1911 - 1914 by way of example. The number of voltage adjustment units can be determined according to the number of LED arrays and the number of LED strings in each LED array. Each of the voltage adjustment units 1911 - 1914 can be individually enabled or disabled by the corresponding enable signal. For example, the voltage adjustment unit 1911 can be controlled by the enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (as shown in Figure 5 ). The voltage adjustment units 1911 - 1914 are coupled to the plurality of discharge ports DIS1 - DIS4 and the plurality of current sensing ports ISEN1 - ISEN8. Specifically, the voltage adjustment unit 1911 is coupled to the first discharge port DIS1 and the current sensing port ISEN1, and is used to short - circuit the first LED string in the first LED array A1 to adjust the voltage on the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0065] Figure 20 Shown is the voltage adjustment unit 1911 in the controller 1980 according to an embodiment of the present invention. In Figure 20 the illustrated embodiment, the voltage adjustment unit 1911 includes a switch 2002. The switch 2002 is coupled between the discharge port DIS1 and the current sensing port ISEN1. When turned on by the enable signal EN1, the switch 2002 conducts the current flowing from the anode of the first LED string in the first LED array A1 to the cathode of the first LED string in the first LED array A1, thereby reducing the voltage on the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0066] Figure 21 Shown is the voltage adjustment unit 1911 in the controller 1980 according to an embodiment of the present invention. In Figure 21In the illustrated embodiment, the voltage regulation unit 1911 includes a current mirror 2101. A first branch of the current mirror 2101 is coupled between the discharge port DIS1 and the current sensing port ISEN1, and a second branch of the current mirror 2101 is coupled between the current source 2102 and the current sensing port ISEN1. A switch 2103 is coupled to the current mirror 2101 for enabling or disabling the current mirror 2101 according to an enable signal EN1. When enabled, the current mirror 2101 conducts the current flowing from the anode of the first LED string in the first LED array A1 through the first branch to the cathode of the first LED string in the first LED array A1, thereby reducing the voltage across the first LED string in the first LED array A1 to be lower than the conduction threshold.

[0067] Continuing to refer to Figure 19 , according to different timing schemes, the voltage regulation unit 1911 can be enabled when the enable signal EN1 is at a first level (e.g., logic high), or disabled when the enable signal EN1 is at a second level (e.g., logic low). In one embodiment, as Figure 22 illustrated, when the first switch SW1 is open, the voltage regulation unit 1911 can be enabled. In another embodiment, as Figure 23 illustrated, the voltage regulation unit 1911 can be enabled during the time interval sequence BBM. The time interval sequence BBM is the interval between four discrete time slots in which the switches SW1 - SW4 are mutually exclusive and turned on. In other words, during each interval in the time interval sequence BBM, none of the switches SW1 - SW4 is turned on, while the voltage regulation unit 1911 is enabled.

[0068] Figure 24 Shown is a light source driving circuit 2400 including a controller 1980 for controlling a light source module according to an embodiment of the present invention. Elements having the same reference numerals as Figure 19 have similar functions. In Figure 24In the illustrated embodiment, the plurality of switches SW1 - SW4 are all p-type metal oxide semiconductor (PMOS) transistors. Each of the plurality of drive ports DRVP1 - DRVP4 is coupled to the gate of a corresponding one of the plurality of switches SW1 - SW4 through an n-type metal oxide semiconductor (NMOS) transistor. Wherein, the gate of the NMOS transistor is coupled to a power supply (e.g., coupled to the power converter 120 through port PWIN). Each of the plurality of discharge ports DIS1 - DIS4 is coupled to a corresponding one of the common nodes N1 - N4 through an NMOS transistor. Wherein, the gate of the NMOS transistor is also coupled to the power supply (e.g., coupled to the power converter 120 through port PWIN). With such a structure, the controller 1980 can work with a light source module in which the input voltage VLED exceeds the tolerance voltage of the controller 1980. A similar structure is also applicable to Figure 5 the controller 580 shown in Figure 12 and the controller 1280 shown in

[0069] As described above, the present invention discloses a controller for controlling a light source module. When a certain LED string in the light source module should not be lit, the controller adjusts the voltage across the LED string to be lower than the conduction threshold. Thus, the LED string will not be inadvertently lit, thereby eliminating the phenomenon of residual images on the display device.

[0070] The above specific embodiments and the drawings are only common embodiments of the present invention. Obviously, various additions, modifications, and substitutions can be made without departing from the spirit and scope of the present invention defined by the claims. Those skilled in the art should understand that the present invention can vary in form, structure, layout, proportion, material, elements, components, and other aspects according to the specific environment and working requirements in actual applications without departing from the invention criteria. Therefore, the embodiments disclosed herein are for illustrative purposes only and not for limitation. The scope of the present invention is defined by the appended claims and their legal equivalents, rather than being limited to the previous description.

Claims

1. A controller for controlling a light source module including a first light emitting diode (LED) array and a second LED array, wherein the first LED array includes a first group of LED strings, the second LED array includes a second group of LED strings, and the controller includes: A first drive port coupled to a first switch, wherein the first switch is coupled between a power converter and the first LED array; A second drive port coupled to a second switch, wherein the second switch is coupled between the power converter and the second LED array; A plurality of current sensing ports coupled to the first LED array and the second LED array for sensing the current of each LED string in the first LED array and the current of each LED string in the second LED array respectively; And A voltage regulating unit coupled to a first LED string in the first LED array for regulating the voltage across the first LED string in the first LED array to make the voltage across the first LED string in the first LED array lower than a threshold; Wherein anodes of the first group of LED strings are connected to a first common node, and the first common node is connected to the first switch, Wherein anodes of the second group of LED strings are connected to a second common node, and the second common node is connected to the second switch, Wherein cathodes of the first LED string in the first LED array and the first LED string in the second LED array are both connected to a third common node, and the third common node is connected to a first current sensing port among the plurality of current sensing ports, and Wherein the controller is configured to turn on the first switch through the first drive port in a first discrete time slot sequence to transfer electrical energy from the power converter to the first LED array; And is configured to turn on the second switch through the second drive port in a second discrete time slot sequence to transfer electrical energy from the power converter to the second LED array, wherein the first discrete time slot sequence and the second discrete time slot sequence are mutually exclusive.

2. The controller according to claim 1, wherein, The controller further includes a first discharge port coupled to the first common node, wherein the voltage regulating unit is coupled to the first discharge port and is configured to reduce the voltage on the anode of the first LED string in the first LED array to make the voltage across the first LED string in the first LED array lower than the threshold.

3. The controller according to claim 2, wherein The voltage regulating unit includes: A discharge switch coupled between the first discharge port and ground; and An amplifier, wherein a non-inverting input terminal of the amplifier receives a first voltage signal, an inverting input terminal of the amplifier is coupled to the first discharge port, and an output terminal of the amplifier is coupled to the discharge switch.

4. The controller according to claim 2, wherein, The voltage regulating unit includes: A discharge switch coupled between the first discharge port and ground; and A comparator, wherein the non-inverting input terminal of the comparator receives a second voltage signal, the inverting input terminal of the comparator is coupled to the first discharge port, and the output terminal of the comparator is coupled to the discharge switch.

5. The controller according to claim 2, wherein The voltage regulating unit includes a discharge switch, and the discharge switch is coupled between the first discharge port and the ground.

6. The controller according to claim 2, wherein, The voltage regulating unit includes a current mirror. A first branch of the current mirror is coupled between the first discharge port and the ground, and a second branch of the current mirror is coupled between a current source and the ground.

7. The controller according to claim 2, wherein, When the first switch is in an off state, the voltage regulating unit is enabled.

8. The controller according to claim 2, wherein The voltage regulating unit is enabled during a time interval sequence between the first discrete time slot sequence and the second discrete time slot sequence, wherein the first switch and the second switch are in an off state during the time interval sequence.

9. The controller according to claim 2, wherein, The first switch includes a p-type metal oxide semiconductor transistor. The first drive port is coupled to the gate of the p-type metal oxide semiconductor transistor through a first n-type metal oxide semiconductor transistor. The first discharge port is coupled to the first common node through a second n-type metal oxide semiconductor transistor. The gates of the first n-type metal oxide semiconductor transistor and the second n-type metal oxide semiconductor transistor are both coupled to a power supply.

10. The controller according to claim 1, wherein, The controller further includes a power supply port coupled to the power converter. The voltage regulating unit is coupled to the power supply port and the first current sensing port and is configured to increase the voltage on the cathode of the first light emitting diode string in the first light emitting diode array so that the voltage on the first light emitting diode string in the first light emitting diode array is lower than the threshold.

11. The controller according to claim 10, wherein, The voltage regulating unit includes: A charging switch, coupled between the power supply port and the first current sensing port; and An amplifier, wherein the non-inverting input terminal of the amplifier receives a third voltage signal, the inverting input terminal of the amplifier is coupled to the first current sensing port, and the output terminal of the amplifier is coupled to the charging switch.

12. The controller according to claim 10, wherein, The voltage regulating unit includes: A charging switch, coupled between the power supply port and the first current sensing port; and A comparator, the non-inverting input terminal of the comparator receives a fourth voltage signal, the inverting input terminal of the comparator is coupled to the first current sensing port, and the output terminal of the comparator is coupled to the charging switch.

13. The controller according to claim 10, wherein The voltage regulating unit includes a charging switch, and the charging switch is coupled between the power supply port and the first current sensing port.

14. The controller according to claim 10, wherein, The voltage regulating unit includes a current mirror. A first branch of the current mirror is coupled between the power supply port and the first current sensing port, and a second branch of the current mirror is coupled between the power supply port and a current source.

15. The controller according to claim 10, wherein, The voltage regulating unit is enabled during a time interval sequence between the first discrete time slot sequence and the second discrete time slot sequence, wherein the first switch and the second switch are in an off state during the time interval sequence.

16. The controller according to claim 1, wherein, The controller further includes a first discharge port coupled to the first common node, wherein the voltage regulation unit is coupled to the first discharge port and the first current sensing port, and is configured to short-circuit the first light-emitting diode string in the first light-emitting diode array, so that the voltage across the first light-emitting diode string in the first light-emitting diode array is lower than the threshold.

17. The controller according to claim 16, wherein, The voltage regulation unit includes a switch coupled between the first discharge port and the first current sensing port.

18. The controller according to claim 16, wherein, The voltage regulation unit includes a current mirror, a first branch of the current mirror is coupled between the first discharge port and the first current sensing port, and a second branch of the current mirror is coupled between a current source and the first current sensing port.

19. The controller according to claim 16, wherein, When the first switch is in the off state, the voltage regulation unit is enabled.

20. The controller according to claim 16, wherein, The voltage regulation unit is enabled during a time interval sequence between the first discrete time slot sequence and the second discrete time slot sequence, wherein the first switch and the second switch are in the off state during the time interval sequence.

21. A controller, coupled to a power supply, for controlling a light source module including a first light-emitting diode array and a second light-emitting diode array, wherein the first light-emitting diode array includes a first set of light-emitting diode strings, the second light-emitting diode array includes a second set of light-emitting diode strings, and the controller includes: A decoding module, configured to receive a timing signal from a timing controller, and generate switch signals according to the timing signal to control a first switch and a second switch, wherein the first switch is coupled between a power converter and the first light-emitting diode array, and the second switch is coupled between the power converter and the second light-emitting diode array; And A residual image elimination module, coupled to the decoding module, configured to adjust the voltage across each light-emitting diode string in the first light-emitting diode array, so that the voltage across each light-emitting diode string in the first light-emitting diode array is lower than a threshold, and is further configured to adjust the voltage across each light-emitting diode string in the second light-emitting diode array, so that the voltage across each light-emitting diode string in the second light-emitting diode array is lower than the threshold, wherein the decoding module is configured to turn on the first switch during a first discrete time slot sequence, and is further configured to turn on the second switch during a second discrete time slot sequence, wherein the first discrete time slot sequence and the second discrete time slot sequence are mutually exclusive.

22. The controller according to claim 21, wherein, The residual image elimination module includes a voltage regulation unit, the voltage regulation unit is coupled to the anode of the first light-emitting diode string in the first light-emitting diode array, wherein the voltage regulation unit is configured to reduce the voltage at the anode of the first light-emitting diode string in the first light-emitting diode array, so that the voltage across the first light-emitting diode string in the first light-emitting diode array is lower than the threshold.

23. The controller according to claim 21, wherein, The residual image elimination module includes a voltage regulation unit, and the voltage regulation unit is coupled to the cathode of the first light-emitting diode string in the first light-emitting diode array. Wherein, the voltage regulation unit is used to increase the voltage on the cathode of the first light-emitting diode string in the first light-emitting diode array, so that the voltage on the first light-emitting diode string in the first light-emitting diode array is lower than the threshold value.

24. The controller according to claim 21, wherein, The residual image elimination module includes a voltage regulation unit, and the voltage regulation unit is coupled to the first light-emitting diode string in the first light-emitting diode array. Wherein, the voltage regulation unit is used to short-circuit the first light-emitting diode string in the first light-emitting diode array, so that the voltage on the first light-emitting diode string in the first light-emitting diode array is lower than the threshold value.

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