CN115311986A

CN115311986A - Controller for controlling light source module

Info

Publication number: CN115311986A
Application number: CN202110865914.4A
Authority: CN
Inventors: 胡荣; 林永霖; 藤田直幸
Original assignee: O2micro Electronics Wuhan Co ltd
Current assignee: O2micro Electronics Wuhan Co ltd
Priority date: 2021-05-06
Filing date: 2021-07-29
Publication date: 2022-11-08
Also published as: JP7105979B1; TWI805345B; TW202244882A; JP2022173035A

Abstract

The 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 comprises a first driving port, a second driving port and a plurality of current sensing ports. The first drive port is coupled to the first switch. The second drive port is coupled to the second switch. The plurality of current sensing ports are used for respectively 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. The controller is used for turning on the first switch through the first driving port in the first discrete time slot sequence so as to transfer the electric energy from the power converter to the first light-emitting diode array; and is further configured to turn on a second switch via a second drive port in a second sequence of discrete time slots to transfer power from the power converter to the second array of light emitting diodes, wherein the first sequence of discrete time slots and the second sequence of discrete time slots are mutually exclusive.

Description

Controller for controlling light source module

Technical Field

The invention relates to the technical field of controllers, in particular to a controller for controlling a light source module.

Background

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 a plurality of LED strings used for backlighting. Since the controller has only a specified number of control pins, the controller can control only a limited number of LED strings. To control a larger number of LED strings, a larger number of controllers are also required, which also increases the cost of the system.

Disclosure of Invention

The 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 set of light emitting diode strings and the second light emitting diode array includes a second set of light emitting diode strings. The controller comprises a first driving port, a second driving port and a plurality of current sensing ports. The first drive port is coupled to a first switch, wherein the first switch is coupled between the power converter and the first light emitting diode array; the second drive port is coupled to a second switch, wherein the second switch is coupled between the power converter and the second light emitting diode array; the plurality of current sensing ports are coupled to the first light emitting diode array and the second light emitting diode array and used for respectively 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; wherein anodes of the first plurality of led strings are connected to a first common node, wherein the first common node is connected to a first switch, wherein anodes of the second plurality of led strings are connected to a second common node, wherein the second common node is connected to a second switch, wherein cathodes of the first led strings in the first led array and cathodes of the first led strings in the second led array are both connected to a third common node, wherein the third common node is connected to a first current sense port of the plurality of current sense ports, and wherein the controller is configured to turn on the first switch at a first sequence of discrete time slots via the first drive port to transfer electrical energy from the power converter to the first led array; the second switch is switched on through the second driving port in a second discrete time slot sequence so as to transfer the electric energy from the power converter to the second light-emitting diode array; wherein the first and second sequences of discrete time slots are mutually exclusive.

The invention also provides a controller. The controller is coupled to the power supply for controlling a light source module comprising a first light emitting diode array and a second light emitting diode array. The first LED array includes a first set of LED strings and the second LED array includes a second set of LED strings. The controller includes a decoding module and a residual image removal module. The decoding module is used for receiving a time sequence signal from the time sequence controller and generating a switch signal according to the time sequence signal so as to control a first switch and a second switch, wherein the first switch is coupled between the 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 the residual image eliminating module is coupled to the decoding module and used for adjusting the voltage on each light emitting diode string in the first light emitting diode array so that the voltage on each light emitting diode string in the first light emitting diode array is lower than a threshold value and adjusting the voltage on each light emitting diode string in the second light emitting diode array so that the voltage on each light emitting diode string in the second light emitting diode array is lower than the threshold value, wherein the decoding module is used for switching on the first switch in a first discrete time slot sequence and switching 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.

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 below the turn-on threshold. Therefore, the LED string is not unintentionally lit, thereby eliminating a residual image phenomenon on the display device.

Drawings

The objects, specific structural features and advantages of the present invention may be further understood by the following description in conjunction with the several embodiments of the present invention and the accompanying drawings.

Fig. 1 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

fig. 2 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

fig. 3 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 4 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

fig. 5 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

FIG. 6 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 7 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 8 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 9 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

fig. 10 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 11 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 12 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

FIG. 13 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 14 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 15 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 16 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

fig. 17 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 18 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 19 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention;

FIG. 20 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

FIG. 21 illustrates a voltage regulation unit in a controller according to one embodiment of the present invention;

fig. 22 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention;

fig. 23 is a timing diagram illustrating a controller for controlling a light source module according to an embodiment of the present invention; and

fig. 24 illustrates a light source driving circuit including a controller for controlling a light source module according to an embodiment of the present invention.

Detailed Description

Hereinafter, a detailed description will be given of embodiments of the present invention. While the invention is illustrated and described in connection with these embodiments, it should be understood that the invention is not limited to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail. In order to highlight the subject matter of the invention.

Fig. 1 illustrates 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 the example of fig. 1, the Light source module includes 4 Light-Emitting Diode (LED) arrays A1, A2, A3, and A4. Wherein each LED array comprises a plurality (e.g., 8) LED strings. This embodiment may serve as the basis for the discussion below, but includes, but is not limited to, 4 LED arrays and/or 8 LED strings per array.

The controller 180 receives power from the power converter 120. The power converter 120 is coupled between the controller 180 and the power source 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 sense 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.

The power input port PWIN is coupled to the power source 110 through the power converter 120 for receiving power from the power converter 120. The power output ports PWO1-PWO4 are correspondingly coupled to the LED arrays A1-A4, respectively. The controller 180 is configured to deliver power to the LED arrays A1-A4 at first, second, third, and fourth discrete time slot sequences, respectively, via the power output ports PWO1-PWO 4. The first, second, third and fourth discrete time slot sequences do not overlap, i.e. they do not overlap in time.

Specifically, the switch 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, a first switch SW1 is coupled between the power input port PWIN and the first power output port PWO1, and a second switch SW2 is coupled between the power input port PWIN and the second power output port PWO2. Referring to fig. 3, the controller 180 is configured to turn on the first switch SW1 in the first discrete time slot sequences T11, T12, T13, turn on the second switch SW2 in the second discrete time slot sequences T21, T22, T23, turn on the third switch SW3 in the third discrete time slot sequences T31, T32, T33, and turn on the fourth switch SW4 in the fourth discrete time slot sequences T41, T42, T43. As shown in fig. 3, the first, second, third and fourth sequences of discrete time slots do not overlap (i.e., they do not occur simultaneously, they do not overlap in time), and are interleaved with one another.

With continued reference to fig. 1, the current sensing ports ISEN1-ISEN8 are respectively coupled to the LED arrays A1-A4 for sensing the magnitude of the current of each LED string in the LED arrays A1-A4, which will be described below. The current regulation module 150 is coupled to the LED arrays A1-A4 via current sensing ports ISEN1-ISEN8 and is used to linearly regulate the current of each LED string in the LED arrays A1-A4, as will be described in detail in FIG. 2.

Referring to fig. 1, the feedback control port 140 is configured to generate a feedback signal FB to control the power converter 120 according to the power requirement of the light source module, so that the power from the power converter 120 can meet the power requirement of the light source module. The feedback signal FB is provided to the power converter 120 through the feedback port FBOUT. The feedback control module 140 is coupled to the current sensing ports ISEN1-ISEN8 and generates the feedback signal FB according to the voltages at the current sensing ports ISEN1-ISEN8. The voltage on the current sense ports ISEN1-ISEN8 may indicate the power requirements of the light source modules. Specifically, the feedback control module 140 selects a minimum voltage of the voltages at 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 power to make the minimum voltage within the preset voltage range.

The decoding module 160 is used for receiving a timing signal from a timing controller 190 (e.g., a micro control unit) and generating a switch signal according to the timing signal to control the switches SW1 to SW4 in the switch module 130. The decoding module 160 is also used to generate a plurality of control signals to control the current regulating module 150. Accordingly, the plurality of current regulating units (as shown in fig. 2) may be individually enabled or disabled according to the corresponding control signals. For example, the decoding module 160 may communicate with the timing controller 190 through a Serial Peripheral Interface (SPI).

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

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

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

Fig. 2 illustrates a light source driving circuit 200 including a controller 180 for controlling a light source module according to an embodiment of the present invention. Fig. 2 shows a detailed view of the internal structure of the controller 180. The controller 180 includes a switching module 130, a feedback control module 140, a current regulation module 150, and a decoding module 160.

The current regulation module 150 includes a plurality of current regulation units 230_1-230_8. The plurality of current adjusting units 230_1-230 _8are respectively coupled to the current sensing ports ISEN1-ISEN8 and are used to linearly adjust the current of each LED string in the LED arrays A1-A4. Each current regulating unit is independently enabled and disabled according to a corresponding control signal of the control signals PWM1-PWM8. The control signals PWM1-PWM8 may be Pulse Width Modulation (PWM) signals.

Specifically, current regulation units 230_1-230 _8correspondingly include amplifiers 290_1-290_8, respectively. Amplifiers 290_1-290 _8are correspondingly coupled to switches Q1-Q8, respectively. Switches Q1-Q8 are each coupled in series with a corresponding LED string. Each current regulating unit has a similar structure. Take the current adjusting unit 230 \u1 as an example. The non-inverting input of amplifier 290\ 1 receives a reference signal ADJ1 indicative of the target current. The inverting input of amplifier 290 u 1 receives sense signal IS1 indicating the magnitude of the current flowing through the corresponding LED string. Amplifier 290 u 1 compares reference signal ADJ1 with sense signal IS1 to generate error signal EA1 and uses error signal EA1 to linearly control switch Q1 to adjust the current of the corresponding LED string so that the current IS at the target current. The switch Q1 is linearly controlled, which means that the switch Q1 is not completely turned on or completely turned off, but may be partially turned on so that the magnitude of the current flowing through the switch Q1 may be continuously (non-discretely) and gradually adjusted.

Amplifier 290, u 1 is controlled by control signal PWM 1. If control signal PWM1 is in a first state (e.g., logic high), amplifier 290 u 1 is enabled while the corresponding LED string is turned on and regulated as described above. If the control signal PWM1 is in a second state (e.g., logic low), the amplifier 290 xu 1 is disabled while the corresponding LED string is turned off.

In one embodiment, the decoding module 160 includes an SPI decoder 210, a PWM generator 220, a Digital-to-Analog converter (DAC) 240, and a reference signal selection unit 250. The SPI decoder 210 receives a timing signal from a timing controller (not shown) and decodes the timing signal. The PWM generator 220 is coupled to the SPI decoder 210 and generates the control signals PWM1 to PWM8 according to the timing signal. DAC 240 is coupled to SPI decoder 210 and generates reference signals ADJ1-ADJ8. The reference signal selection unit 250 selects either the reference signals ADJ1-ADJ8 or the system reference signal SYS _ REF and provides the selected signal (e.g., ADJ1-ADJ8 or SYS _ REF) to the corresponding amplifier 290 \u1-290 \u8. Wherein the system reference signal SYS _ REF is also generated from the SPI decoder 210. In other words, either the non-inverting input of amplifier 290 xu 1 receives the reference signal ADJ1, the non-inverting input of amplifier 290 xu 2 receives the reference signal ADJ2, etc., or the non-inverting inputs of amplifiers 290 xu 1-290 xu 8 all receive the system reference signal SYS _ REF. Further, the decoding module 160 processes the timing signal and provides the switching signal to the switching module 130. The switch module 130 controls the switches SW1-SW4 with switch signals to turn on the switches SW1-SW4 in four discrete time slot sequences that do not overlap each other.

As previously mentioned, the present invention includes a controller for controlling a light source module. The controller is used to selectively deliver electrical energy to the 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 also to regulate the current to each LED string in the plurality of LED arrays. The controller allows the plurality of LED arrays to share the same set of current sensing ports in the controller. Advantageously, multiple 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, allowing Xu Linghuo and fine dimming in the display system.

Fig. 4 illustrates 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 having the same reference number as in fig. 1 have similar functions. Fig. 4 will be described in conjunction with fig. 1. The embodiment shown in fig. 4 differs from the embodiment shown in fig. 1 mainly in that the switch module 130 in fig. 1 is located inside the controller 180, whereas the switch module 130 in fig. 4 is located outside the controller 480. The controller 480 is correspondingly coupled to the switches SW1 to SW4 through a plurality of driving ports DRVP1 to DRVP4, respectively. The switch SW1 is coupled between the power converter 120 and the first LED array A1. The switch SW2 is coupled between the power converter 120 and the second LED array A2. The switch SW3 is coupled between the power converter 120 and the third LED array A3. The 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 magnitude of current flowing through the LED strings in the LED arrays A1-A4. Anodes of the LED strings in the first LED array A1 are connected to a common node N1, and the common node N1 is connected to the switch SW1. The anodes of the LED strings in the second LED array A2 are connected to a common node N2, and the common node N2 is connected to the switch SW2. The anodes of the LED strings in the third LED array A3 are connected to a common node N3, and the common node N3 is connected to the switch SW3. Anodes of the LED strings in the fourth LED array A4 are connected to a common node N4, and the common node N4 is connected to the switch SW4. The cathode of the first LED string in the first LED array A1, the cathode of the first LED string in the second LED array A2, the cathode of the first LED string in the third LED array A3 and the cathode of the first LED string in the fourth LED array A4 are all connected with the first common node NC1. The first common node NC1 is connected to a current sensing port ISEN1. Thus, the current sensing port ISEN1 senses the current on the first LED string in each LED array. Similarly, the cathode of the second LED string in each LED array is connected to a second common node NC2 (not shown). The second common node NC2 is connected to a current sensing port ISEN2 (not shown). By analogy, the cathode of the last (e.g., 8 th) LED string in each LED array is connected to the corresponding (e.g., 8 th) common node NC8. The common node NC8 is connected to a current sensing port ISEN8.

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

Since the switches SW1-SW4 are usually implemented by Metal Oxide Semiconductor (MOS) transistors including parasitic capacitors, when one LED string (e.g., the first LED string in the first LED array A1) is turned off by turning off the switch SW1, if the switch Q1 (in the current regulating module 150 shown in fig. 2) is turned on at this time, the parasitic capacitors flowing through the switch SW1 generate a spike current flowing to the ground through the switch Q1. Such a spike current may 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 produce an undesirable residual image on the screen of the display device. To address this problem, various embodiments according to the present invention are disclosed in fig. 5 to 24.

Fig. 5 illustrates a light source driving circuit 500 including a controller 580 for controlling a light source module according to an embodiment of the present invention. Elements having the same reference number as in fig. 4 have similar functions. In the embodiment shown in fig. 5, the controller 580 includes a plurality of discharge ports DIS1-DIS4, each coupled to the anode of each LED string in a corresponding LED array. For example, the discharge port DIS1 is coupled to an anode (e.g., common node N1) of each LED string in the first LED array A1. The discharge port DIS2 is coupled to an anode (e.g., a common node N2) of each LED string in the second LED array A2, and the like. The controller 580 includes a residual image removal module 501. The residual image removal module 501 is coupled to the decoding module 160 and is used to adjust the voltage across each LED string in each LED array to be below a threshold (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 adjusting units may be determined according to the number of LED arrays and the number of LED strings in each LED array. Each of the voltage regulating units 511-514 may be individually enabled or disabled by a corresponding enable signal. For example, the adjusting unit 511 may be controlled by an enable signal EN1. The enable signal EN1 is generated by the decode module 160 (shown in FIG. 5). The voltage adjusting units 511-514 are correspondingly coupled to the plurality of discharge ports DIS1-DIS4, respectively. Specifically, the voltage adjusting unit 511 is coupled to the first discharge port DIS1, and is configured to reduce a voltage across an anode of the first LED string in the first LED array A1 to adjust the voltage across the first LED string in the first LED array A1 to be lower than a threshold value.

Fig. 6 shows a voltage regulating unit 511 in a controller 580 according to an embodiment of the present invention. In the embodiment shown in fig. 6, the voltage regulating unit 511 includes an amplifier 601 and a discharge switch 602. Discharge switch 602 is coupled between discharge port DIS1 and ground. The non-inverting input of the amplifier 601 receives the first voltage signal V1, the inverting input of the amplifier 601 is coupled to the discharge port DIS1, and the output of the amplifier 601 is coupled to the discharge switch 602. When enabled by enable signal EN1, amplifier 601 adjusts the voltage on the anode of the first LED string in first LED array A1 to follow first voltage signal V1, thereby reducing the voltage on the first LED string in first LED array A1 to below the turn-on threshold.

Fig. 7 shows a voltage regulating unit 511 in a controller 580 according to an embodiment of the present invention. In the embodiment shown in fig. 7, the voltage adjusting unit 511 includes a comparator 701 and a discharge switch 702. Discharge switch 702 is coupled between discharge port DIS1 and ground. A non-inverting input of the comparator 701 receives the second voltage signal V2, an inverting input of the comparator 701 is coupled to the discharge port DIS1, and an output of the comparator 701 is coupled to the discharge switch 702. When enabled by the enable signal EN1, the comparator 701 compares the voltage at 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 turn on the discharge current flowing from the anode of the first LED string in the first LED array A1 to the ground through the discharge switch 702, thereby reducing the voltage on the first LED string in the first LED array A1 to be lower than the turn-on threshold.

Fig. 8 shows a voltage regulating unit 511 in a controller 580 according to an embodiment of the present invention. In the embodiment shown in fig. 8, the voltage adjusting unit 511 includes a discharge switch 802. The discharge switch 802 is coupled between the discharge port DIS1 and ground. When turned on by the enable signal EN1, the discharge switch 802 turns on a discharge current flowing from the anode of the first LED string in the first LED array A1 to ground, thereby reducing the voltage across the first LED string in the first LED array A1 to be below a turn-on threshold.

Fig. 9 shows a voltage regulating unit 511 in a controller 580 according to an embodiment of the present invention. In the embodiment shown in fig. 9, the voltage regulating unit 511 comprises a current mirror 901. The current mirror 901 has a first branch coupled between the discharge port DIS1 and ground and a second branch coupled between the current source 902 and ground. The switch 903 is coupled to the current mirror 901, and is used for enabling or disabling the current mirror 901 according to an enable signal EN1. When enabled, the current mirror 901 turns on the discharge current flowing from the anode of the first LED string in the first LED array A1 through the first branch to ground, thereby reducing the voltage across the first LED string in the first LED array A1 to be below the turn-on threshold.

With continued reference to fig. 5, according to different timing schemes, the voltage adjusting unit 511 may be enabled when the enable signal EN1 is at a first level (e.g., logic high), or the voltage adjusting unit 511 may be disabled when the enable signal EN1 is at a second level (e.g., logic low). In one embodiment, the voltage regulating unit 511 may be enabled all the time. In another embodiment, as shown in fig. 10, when the first switch SW1 is turned off, the voltage regulating unit 511 may be enabled. In another embodiment, as shown in fig. 11, the voltage regulating unit 511 may be enabled in 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 turned on mutually exclusively. In other words, at each interval in the time interval sequence BBM, any one of the switches SW1 to SW4 is not turned on while the voltage regulating unit 511 is enabled.

Fig. 12 illustrates a light source driving circuit 1200 including a controller 1280 for controlling the light source module according to one embodiment of the present invention. Elements having the same reference number as in fig. 4 have similar functions. The controller 1280 includes a power port VLEDIN coupled to the power converter 120. The controller 1280 also includes a residual image removal module 1201 coupled to the decoding module 160. The residual image removal module 1201 is used to adjust the voltage across each LED string in each LED array to be below 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 removal module 1201 includes a plurality of voltage adjustment units, such as voltage adjustment units 1211-1214 as an example. The number of voltage adjusting units may be determined according to the number of LED arrays and the number of LED strings in each LED array. Each of the voltage regulating units 1211-1214 may be individually enabled or disabled by a corresponding enable signal. For example, the adjusting unit 1211 may be controlled by an enable signal EN1. The enable signal EN1 is generated by the decode module 160 (shown in FIG. 5). The voltage regulation units 1211-1214 are coupled to the power port VLEDIN and the plurality of current sensing ports ISEN1-ISEN8. Specifically, the voltage adjusting unit 1211 is coupled to the power supply port VLEDIN and the current sensing port ISEN1, and is configured to increase the voltage at the cathode of the first LED string in the first LED array A1 to adjust the voltage at the first LED string in the first LED array A1 to be lower than the threshold.

Fig. 13 shows a voltage regulation unit 1211 in a controller 1280 according to one embodiment of the present invention. In the embodiment shown in fig. 13, the voltage regulation unit 1211 includes an amplifier 1301 and a charging switch 1302. The charging switch 1302 is coupled between the power port VLEDIN and the current sensing port ISEN1. The non-inverting input of the amplifier 1301 receives the third voltage signal V3, the inverting input of the amplifier 1301 is coupled to the current sensing port ISEN1, and the output of the amplifier 1301 is coupled to the charge switch 1302. When enabled by the enable signal EN1, the amplifier 1301 adjusts 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 on the first LED string in the first LED array A1 to be below the turn-on threshold.

Fig. 14 shows a voltage regulation unit 1211 in a controller 1280 according to one embodiment of the present invention. In the embodiment shown in fig. 14, the voltage adjusting 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 of the comparator 1401 receives the fourth voltage signal V4, the inverting input of the comparator 1401 is coupled to the current sensing port ISEN1, and the output of the comparator 1401 is coupled to the charging switch 1402. When enabled by the 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 turn on the 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 on the first LED string in the first LED array A1 to be lower than the turn-on threshold.

Fig. 15 shows a voltage regulation unit 1211 in a controller 1280 according to one embodiment of the present invention. In the embodiment shown in fig. 15, the voltage regulation unit 1211 includes a charging switch 1502. The charge switch 1502 is coupled between the power supply port VLEDIN and the current sensing port ISEN1. When turned on by the 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 below the conduction threshold.

Fig. 16 shows a voltage regulation unit 1211 in a controller 1280 according to one embodiment of the present invention. In the embodiment shown in fig. 16, the voltage regulation unit 1211 includes a current mirror 1601. A first branch of the current mirror 1601 is coupled between the power port VLEDIN and the current sensing port ISEN1, and a second branch of the current mirror 1601 is coupled between the power port VLEDIN and the current source 1602. The switch 1603 is coupled to the current mirror 1601 for enabling or disabling the current mirror 1601 according to an enable signal EN1. When enabled, the current mirror 1601 conducts a charging current from the power supply port VLEDIN through the first shunt 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 below the conduction threshold.

With continued reference to fig. 12, the voltage regulation unit 1211 may 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) according to different timing schemes. In an embodiment, as shown in fig. 17, the voltage regulation unit 1211 may be enabled in 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 turned on mutually exclusively. In other words, at each interval in the time interval sequence BBM, any one of the switches SW1 to SW4 is not turned on, while the voltage regulation unit 1211 is enabled. In another embodiment, as shown in fig. 18, the voltage regulation unit 1211 may be enabled in the time interval sequence BBM, and the voltage regulation unit 1211 may also be enabled if the corresponding control signal PWM1 (shown in fig. 2) is in the second state (e.g., logic low).

Fig. 19 shows a light source driving circuit 1900 including a controller 1980 for controlling a light source module according to one embodiment of the present invention. Elements having the same reference number as in fig. 4 have similar functions. In the embodiment shown in FIG. 19, controller 1980 includes a plurality of discharge ports DIS1-DIS4, each coupled to the anode of a respective LED string in a corresponding LED array. For example, the discharge port DIS1 is coupled to an anode (e.g., a common node N1) of each LED string in the first LED array A1. The discharge port DIS2 is coupled to an anode (e.g., a common node N2) of each LED string in the second LED array A2, and the like. The controller 1980 includes a residual image removal module 1901. The residual image removal module 1901 is coupled to the decoding module 160 for adjusting the voltage across each LED string in each LED array to be below 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 removal module 1901 includes a plurality of voltage adjustment units, such as, for example, voltage adjustment units 1911-1914. The number of voltage adjusting units may 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 1911-1914 may be individually enabled or disabled via a respective enable signal. For example, the voltage adjustment unit 1911 may be controlled by the enable signal EN1. The enable signal EN1 is generated by the decode module 160 (shown in FIG. 5). Voltage regulation units 1911-1914 are coupled to the plurality of discharge ports DIS1-DIS4 and the plurality of current sense ports ISEN1-ISEN8. Specifically, the voltage adjusting unit 1911 is coupled to the first discharging port DIS1 and the current sensing port ISEN1, and is used for short-circuiting the first LED string in the first LED array A1 to adjust the voltage across the first LED string in the first LED array A1 to be lower than the turn-on threshold.

Fig. 20 shows a voltage regulation unit 1911 in a controller 1980 according to an embodiment of the invention. In the embodiment shown in fig. 20, the voltage regulation unit 1911 includes a switch 2002. Switch 2002 is coupled between discharge port DIS1 and current sense port ISEN1. When turned on by the enable signal EN1, the switch 2002 turns on a 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 across the first LED string in the first LED array A1 to be below the turn-on threshold.

Fig. 21 shows a voltage regulation unit 1911 in a controller 1980 according to an embodiment of the invention. In the embodiment shown in fig. 21, 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. The 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, current mirror 2101 conducts current from the anode of the first LED string in first LED array A1 to the cathode of the first LED string in first LED array A1 via the first shunt branch, thereby reducing the voltage across the first LED string in first LED array A1 to below the conduction threshold.

With continued reference to fig. 19, according to different timing schemes, the voltage adjustment unit 1911 may 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 shown in fig. 22, when the first switch SW1 is turned off, the voltage regulation unit 1911 may be enabled. In another embodiment, as shown in fig. 23, voltage regulation unit 1911 may be enabled for a sequence of time intervals BBM. The time interval sequence BBM is the interval between four discrete time slot sequences in which the switches SW1-SW4 are turned on mutually exclusively. In other words, at 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.

Fig. 24 illustrates 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 number as in fig. 19 have similar functions. In the embodiment shown in fig. 24. 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 a gate of a corresponding switch 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 the power supply (e.g., coupled to the power converter 120 via the port PWIN). Each of the plurality of discharge ports DIS1-DIS4 is coupled to a corresponding one of the common nodes N1-N4 via 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 via the port PWIN). With such a structure, the controller 1980 can operate with the light source module in which the input voltage VLED exceeds the tolerance voltage of the controller 1980. A similar structure is also applicable to the controller 580 shown in fig. 5 and the controller 1280 shown in fig. 12.

The foregoing detailed description and drawings are merely representative of the general embodiments of the invention. It will be apparent that various additions, modifications and substitutions are possible without departing from the spirit and scope of the invention as defined in the accompanying claims. It will be appreciated by those skilled in the art that the present invention may be varied in form, structure, arrangement, proportions, materials, elements, components and otherwise, used in the practice of the invention, depending upon specific environments and operating requirements, without departing from the principles of the present invention. Accordingly, the presently disclosed embodiments are meant to be illustrative only and not limiting, the scope of the invention being defined by the appended claims and their legal equivalents, rather than by the foregoing description.

Claims

1. A controller for controlling a light source module comprising a first light emitting diode array comprising a first set of light emitting diode strings and a second light emitting diode array comprising a second set of light emitting diode strings, the controller comprising:

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 array of light emitting diodes; and

a plurality of current sensing ports coupled to the first and second LED arrays for sensing current of each LED string in the first LED array and each LED string in the second LED array, respectively;

wherein anodes of the first plurality of LED strings are connected to a first common node, wherein the first common node is connected to the first switch,

wherein anodes of the second group of light emitting diode strings are connected to a second common node, wherein the second common node is connected to the second switch,

wherein a cathode of a first light emitting diode string in the first light emitting diode array and a cathode of a first light emitting diode string in the second light emitting diode array are both connected to a third common node, wherein the third common node is connected to a first current sense port of the plurality of current sense ports, an

Wherein the controller is configured to turn on the first switch at a first sequence of discrete time slots via the first drive port to transfer power from the power converter to the first array of light emitting diodes; and means for turning on the second switch at a second sequence of discrete time slots through the second drive port to transfer power from the power converter to the second array of light emitting diodes, wherein the first and second sequences of discrete time slots are mutually exclusive.

2. The controller of claim 1, further comprising a voltage adjustment unit coupled to the first string of light emitting diodes in the first light emitting diode array for adjusting a voltage across the first string of light emitting diodes in the first light emitting diode array such that the voltage across the first string of light emitting diodes in the first light emitting diode array is below a threshold.

3. The controller of claim 2, wherein the controller further comprises a first discharge port coupled to the first common node, wherein the voltage adjustment unit is coupled to the first discharge port and is configured to reduce the voltage across the anodes of the first light emitting diode strings in the first light emitting diode array such that the voltage across the first light emitting diode strings in the first light emitting diode array is below the threshold.

4. The controller of claim 3, wherein the voltage regulation unit comprises:

a discharge switch coupled between the first discharge port and ground; and

an amplifier, wherein a non-inverting input of the amplifier receives a first voltage signal, an inverting input of the amplifier is coupled to the first discharge port, and an output of the amplifier is coupled to the discharge switch.

5. The controller of claim 3, wherein the voltage regulation unit comprises:

a discharge switch coupled between the first discharge port and ground; and

a comparator, wherein a non-inverting input of the comparator receives a second voltage signal, an inverting input of the comparator is coupled to the first discharge port, and an output of the comparator is coupled to the discharge switch.

6. The controller of claim 3, wherein the voltage regulation unit comprises a discharge switch coupled between the first discharge port and ground.

7. The controller of claim 3, wherein the voltage regulation unit comprises a current mirror, a first branch of the current mirror coupled between the first discharge port and ground, a second branch of the current mirror coupled between a current source and ground.

8. The controller of claim 3, wherein the voltage regulation unit is enabled when the first switch is in an off state.

9. The controller of claim 3, wherein the voltage adjustment unit is enabled for a sequence of time intervals between the first sequence of discrete time slots and the second sequence of discrete time slots, wherein the first switch and the second switch are in an open state in the sequence of time intervals.

10. The controller of claim 3, wherein the first switch comprises a p-type metal-oxide-semiconductor transistor, wherein the first drive port is coupled to a gate of the p-type metal-oxide-semiconductor transistor through a first n-type metal-oxide-semiconductor transistor, wherein the first discharge port is coupled to the first common node through a second n-type metal-oxide-semiconductor transistor, wherein a gate of the first n-type metal-oxide-semiconductor transistor and a gate of the second n-type metal-oxide-semiconductor transistor are both coupled to a power supply.

11. The controller of claim 2, wherein the controller further comprises a power port coupled to the power converter, wherein the voltage regulation unit is coupled to the power port and the first current sensing port and is configured to increase the voltage on the cathode of the first LED string in the first LED array such that the voltage on the first LED string in the first LED array is below the threshold.

12. The controller of claim 11, wherein the voltage regulation unit comprises:

a charge switch coupled between the power port and the first current sensing port; and

an amplifier, wherein a non-inverting input of the amplifier receives a third voltage signal, an inverting input of the amplifier is coupled to the first current sense port, and an output of the amplifier is coupled to the charge switch.

13. The controller of claim 11, wherein the voltage regulation unit comprises:

a comparator having a non-inverting input to receive a fourth voltage signal, an inverting input coupled to the first current sense port, and an output coupled to the charge switch.

14. The controller of claim 11, wherein the voltage regulation unit comprises a charge switch coupled between the power port and the first current sensing port.

15. The controller of claim 11, wherein the voltage regulation unit comprises a current mirror, a first branch of the current mirror being coupled between the power port and the first current sensing port, a second branch of the current mirror being coupled between the power port and a current source.

16. The controller of claim 11, wherein the voltage adjustment unit is enabled for a sequence of time intervals between the first sequence of discrete time slots and the second sequence of discrete time slots, wherein the first switch and the second switch are in an open state in the sequence of time intervals.

17. The controller of claim 2, wherein the controller further comprises a first discharge port coupled to the first common node, wherein the voltage adjustment unit is coupled to the first discharge port and the first current sense port and is configured to short the first light emitting diode string in the first light emitting diode array such that a voltage across the first light emitting diode string in the first light emitting diode array is below the threshold.

18. The controller of claim 17, wherein the voltage regulation unit comprises a switch coupled between the first discharge port and the first current sensing port.

19. The controller of claim 17, wherein the voltage regulation unit comprises a current mirror, a first branch of the current mirror coupled between the first discharge port and the first current sense port, a second branch of the current mirror coupled between a current source and the first current sense port.

20. The controller of claim 17, wherein the voltage regulation unit is enabled when the first switch is in an off state.

21. The controller of claim 17, wherein the voltage adjustment unit is enabled for a sequence of time intervals between the first sequence of discrete time slots and the second sequence of discrete time slots, wherein the first switch and the second switch are in an open state in the sequence of time intervals.

22. A controller coupled to a power supply for controlling a light source module comprising a first light emitting diode array comprising a first set of light emitting diode strings and a second light emitting diode array comprising a second set of light emitting diode strings, the controller comprising:

a decoding module for receiving a timing signal from a timing controller and generating a switching signal 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, for adjusting the voltage across each LED string in the first LED array such that the voltage across each LED string in the first LED array is below a threshold value, and for adjusting the voltage across each LED string in the second LED array such that the voltage across each LED string in the second LED array is below the threshold value,

wherein the decoding module is configured to turn on the first switch at a first sequence of discrete time slots and is further configured to turn on the second switch at a second sequence of discrete time slots, wherein the first sequence of discrete time slots and the second sequence of discrete time slots are mutually exclusive.

23. The controller of claim 22, wherein the residual image removal module comprises a voltage adjustment unit coupled to an anode of a first string of light emitting diodes in the first light emitting diode array, wherein the voltage adjustment unit is configured to reduce a voltage across the anode of the first string of light emitting diodes in the first light emitting diode array such that the voltage across the first string of light emitting diodes in the first light emitting diode array is below the threshold.

24. The controller of claim 22, wherein the residual image removal module comprises a voltage adjustment unit coupled to a cathode of a first light emitting diode string in the first light emitting diode array, wherein the voltage adjustment unit is configured to increase a voltage across the cathode of the first light emitting diode string in the first light emitting diode array such that the voltage across the first light emitting diode string in the first light emitting diode array is below the threshold.

25. The controller of claim 22, wherein the residual image removal module comprises a voltage adjustment unit coupled to a first light emitting diode string in the first light emitting diode array, wherein the voltage adjustment unit is configured to short the first light emitting diode string in the first light emitting diode array such that a voltage across the first light emitting diode string in the first light emitting diode array is below the threshold.