CN115311986A - Controller for controlling light source module - Google Patents

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 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 LED string in the first LED array and the current of each LED string in the second LED array. The controller is used for turning on the first switch in the first discrete time slot sequence through the first driving port, so as to transfer the power from the power converter to the first light emitting diode array; and is also used for passing the second driving port, in the second The discrete time slot sequence turns on the second switch to deliver power 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

Controller for controlling the light source module

technical field

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

Background technique

In a light-emitting diode (Light-Emitting Diode, LED) display system, such as a liquid crystal display (Liquid Crystal Display, LCD) television, a controller is usually used to control the power of multiple LED strings used for backlighting. Since the controller only has a specified number of control pins, the controller can only control a limited number of LED strings. In order to control a larger number of LED strings, a larger number of controllers is also required, which also increases the cost of the system.

Contents of the invention

The invention provides a controller for controlling a light source module. The light source module includes a first 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 first driving port, a second driving port and a plurality of current sensing ports. The first drive port is coupled to the first switch, wherein the first switch is coupled between the power converter and the first LED array; the second drive port is coupled to the second switch, wherein the second switch is coupled between the power converter and the second between the LED arrays; and a plurality of current sensing ports coupled to the first LED array and the second LED array for respectively sensing the current of each LED string in the first LED array and the current in the second LED array The current of each light-emitting diode string; wherein the anode of the first group of light-emitting diode strings is connected to the first common node, wherein the first common node is connected to the first switch, and wherein the anode of the second group of light-emitting diode strings is connected to the second common node, wherein the first common node is connected to the second common node. The two common nodes are connected to the second switch, wherein the cathodes of the first light emitting diode string in the first light emitting diode array and the cathodes of the first light emitting diode string in the second light emitting diode array are both connected to the third common node, wherein the third common node connected to a first current sensing port of the plurality of current sensing ports, and wherein the controller is configured to turn on the first switch in a sequence of first discrete time slots through the first driving port to transfer power from the power converter to the first LED array; used to turn on the second switch in the second discrete time slot sequence through the second drive port, so as to transfer the electric energy from the power converter to the second LED array; wherein the first discrete time slot sequence and the second discrete time slot sequence The two discrete time slot sequences are mutually exclusive.

The invention also provides a controller. The controller is coupled to the power supply and is used for controlling the light source module including the first LED array and the 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 used for receiving timing signals from the timing controller, and generating switching signals according to the timing signals to control the first switch and the second switch, wherein the first switch is coupled between the power converter and the first LED array, and the second Two switches are coupled between the power converter and the second LED array; and the residual image elimination module is coupled to the decoding module, and is used for adjusting the voltage on each LED string in the first LED array, so that the first LED array The voltage on each light-emitting diode string in the second light-emitting diode array is lower than the threshold value, and is also used to adjust 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 to turn on the first switch in the first sequence of discrete time slots, and is also used to turn on the second switch in the 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 .

As mentioned 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 on the LED string to make it lower than the conduction threshold. Therefore, the LED string cannot be unintentionally illuminated, thereby eliminating the phenomenon of residual image on the display device.

Description of drawings

The purpose, specific structural features and advantages of the present invention can be further understood through the following descriptions in conjunction with some embodiments of the present invention and the accompanying drawings.

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

FIG. 2 shows 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 of a controller for controlling a light source module according to an embodiment of the present invention;

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

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

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

Fig. 7 shows the voltage regulation unit in the controller according to one embodiment of the present invention;

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

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

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

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

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

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

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

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

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

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

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

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

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

Figure 21 shows a voltage regulation unit in a controller according to an embodiment of the present invention;

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

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

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

Detailed ways

A detailed description will be given below of embodiments of the present invention. Although the present invention has been illustrated and illustrated by these embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, the invention covers all alternatives, modifications and equivalents which are within the spirit and scope of the invention as defined by the appended claims.

In addition, in order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. 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. Described in order to highlight the gist of the present invention.

FIG. 1 shows 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 four light-emitting diode (Light-Emitting Diode, LED) arrays A1 , A2 , A3 and A4 . Each LED array includes multiple (eg, 8) LED strings. This example 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 sensing ports ISEN1-ISEN8. The number of power output ports is equal to the number of LED arrays. The number of current sense ports is equal to the number of LED strings in each LED array. The controller 180 includes a switch 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 used to transmit electric energy to the LED arrays A1 - A4 respectively in the first, second, third and fourth discrete time slot sequences through the power output ports PWO1 - PWO4 . The first, second, third and fourth sequences of discrete time slots are non-overlapping, that is, they have no 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, 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 FIG. 3 , the controller 180 is used to turn on the first switch SW1 in the first discrete time slot sequence T11, T12, T13, and turn on the second switch SW2 in the second discrete time slot sequence T21, T22, T23. The third switch SW3 is turned on in a sequence of three discrete time slots T31 , T32 , T33 , and the fourth switch SW4 is turned on in a fourth sequence of discrete time slots T41 , T42 , T43 . As shown in FIG. 3, the first, second, third and fourth discrete time slot sequences are non-overlapping (that is, they do not occur simultaneously, they do not overlap in time), and are interleaved with each other.

Please continue to refer to FIG. 1 , the current sensing ports ISEN1-ISEN8 are respectively coupled to the LED arrays A1-A4 for sensing the current of each LED string in the LED arrays A1-A4, and the method will be described below. The current regulating module 150 is coupled to the LED arrays A1-A4 through the current sensing ports ISEN1-ISEN8, and is used for linearly regulating the current of each LED string in the LED arrays A1-A4. The specific situation will be introduced in detail in FIG. 2 .

Please continue to refer to FIG. 1 , the feedback control port 140 is used to generate a feedback signal FB to control the power converter 120 according to the power demand of the light source module, so that the power from the power converter 120 can meet the power demand 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 a feedback signal FB according to the voltage on the current sensing ports ISEN1-ISEN8. The voltage 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 a feedback signal FB. Under the control of the feedback signal FB, the power converter 120 increases or decreases the power so that the minimum voltage is within the preset voltage range.

The decoding module 160 is used to receive timing signals from the timing controller 190 (eg, a microcontroller unit), and generate switching signals according to the timing 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 . Correspondingly, multiple current regulating units (as shown in FIG. 2 ) can be individually enabled or disabled according to corresponding control signals. For example, the decoding module 160 can communicate with the timing controller 190 through a serial peripheral interface (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, 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 the first power output port PWO1. In the second LED array A2, the anodes of the LED strings are connected to the common node N2, and the common node N2 is connected to the second power output port PWO2. In the third LED array A3, the anodes of the LED strings are connected to the common node N3, and the common node N3 is connected to the third power output port PWO3. In the fourth LED array A4, the anodes of the LED strings are connected to the common node N4, and the common node N4 is connected to the 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 fourth LED array Cathodes of the first LED strings in 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 sense 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 shown in the figure). By analogy, the cathode of the last (eg, 8th) LED string in each LED array is connected to the corresponding (eg, 8th) common node NC8. The common node NC8 is connected to the current sense 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, the common node N1, reaches the first LED array A1, and then returns to the controller 180 . 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.

FIG. 2 shows 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 switch 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 regulating units 230_1-230_8 are respectively coupled to the current sensing ports ISEN1-ISEN8, and are used for linearly regulating 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 among the control signals PWM1-PWM8. The control signals PWM1-PWM8 may be pulse width modulation (Pulse Width Modulation, PWM) signals.

Specifically, the current adjustment units 230_1-230_8 respectively include amplifiers 290_1-290_8. 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 regulating unit has a similar structure. Take the current regulating unit 230_1 as an example. The non-inverting input terminal of the amplifier 290_1 receives the reference signal ADJ1 indicating the target current. The inverting input terminal of the amplifier 290_1 receives the sensing signal IS1 indicating the magnitude of the current flowing through the corresponding LED string. The amplifier 290_1 compares the reference signal ADJ1 and the sensing signal IS1 to generate an error signal EA1, and utilizes the error signal EA1 to linearly control the switch Q1 to adjust the current of the corresponding LED string so that the current is at the target current. The linear control of the switch Q1 means that the switch Q1 is not completely turned on or completely turned off, but can be partially turned on so that the magnitude of the current flowing through the switch Q1 can be adjusted continuously (non-discretely) and gradually .

The amplifier 290_1 is controlled by the control signal PWM1. If the control signal PWM1 is in the first state (eg, logic high), the amplifier 290_1 is enabled, and the corresponding LED string is turned on and regulated as described above. If the control signal PWM1 is in the second state (eg, logic low), the amplifier 290_1 is disabled and 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-Analog Converter (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. 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 (eg, ADJ1-ADJ8 or SYS_REF) to the corresponding amplifiers 290_1-290_8. Wherein the system reference signal SYS_REF is also generated from the SPI decoder 210 . In other words, either the non-inverting input of the amplifier 290_1 receives the reference signal ADJ1, the non-inverting input of the amplifier 290_2 receives the reference signal ADJ2, etc., or the non-inverting inputs of the amplifiers 290_1-290_8 all receive the system reference signal SYS_REF. Further, the decoding module 160 processes timing signals and provides switching signals to the switching module 130 . The switch module 130 uses the switch signal to control the switches SW1-SW4, and turns on the switches SW1-SW4 in a sequence of four discrete time slots that do not overlap each other.

As previously mentioned, the present invention includes a controller for controlling the light source module. The controller is used to selectively deliver power to multiple LED arrays (for example, first to one LED array, then to another LED array, and so on, only one LED array at a time), and to regulate the power in the multiple LED arrays. current per LED string. The controller enables the multiple 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 multiple LED arrays can be individually dimmed or disabled, allowing flexible and fine-grained dimming in display systems.

FIG. 4 shows a light source driving circuit 400 including a controller 480 for controlling a light source module according to an embodiment of the present invention. Components with the same reference numbers as in FIG. 1 have similar functions. Figure 4 will be introduced in conjunction with Figure 1. The difference between the embodiment shown in FIG. 4 and the embodiment shown in FIG. 1 is mainly that the switch module 130 in FIG. 1 is located inside the controller 180 , while the switch module 130 in FIG. 4 is located outside the controller 480 . The controller 480 is respectively coupled to the switches SW1-SW4 through a plurality of driving ports DRVP1-DRVP4. 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 current of each LED string in the LED arrays A1-A4. 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 switch SW1. 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 switch SW2. 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 switch SW3. 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 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 The cathodes 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 sense 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 shown in the figure). By analogy, the cathode of the last (eg, 8th) LED string in each LED array is connected to the corresponding (eg, 8th) common node NC8. The common node NC8 is connected to the current sense port ISEN8.

The controller 480 is used to turn on the first switch SW1 in the first discrete time slot sequence T11 , T12 , T13 through the first driving port DRVP1 , so as to transfer the electric energy from the power converter 120 to the first LED array A1 . The controller 480 is also used to turn on the second switch SW2 in the second discrete time slot sequence T21 , T22 , T23 through the second driving port DRVP2 , so as to transfer the electric 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 in the third discrete time slot sequence T31 , T32 , T33 through the third drive port DRVP3 , so as to transfer the electric 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 in the fourth discrete time slot sequence T41 , T42 , T43 through the fourth drive port DRVP4 , so as to transfer the electric energy from the power converter 120 to the fourth LED array A4 . As shown in FIG. 3, the first, second, third and fourth discrete time slot sequences are non-overlapping and interleaved with each other. Specifically, the decoding module 160 is configured to receive timing signals from the timing controller 190 and generate switching signals to control the plurality of switches SW1 - SW4 as described above.

Since the switches SW1-SW4 are usually implemented by metal-oxide-semiconductor (MOS) transistors containing parasitic capacitance, when an LED string (for example, the first LED string in the first LED array A1) is turned off by turning off the switch SW1, if At this moment, the switch Q1 (in the current regulation module 150 shown in FIG. 2 ) is in the on state, and a peak current will flow through the parasitic capacitance of the switch SW1 and flow to the ground through the switch Q1. 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 computer monitor, this will produce 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 FIGS. 5 to 24 .

FIG. 5 shows a light source driving circuit 500 including a controller 580 for controlling a light source module according to an embodiment of the present invention. Components with the same reference numbers 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, and each discharge port is coupled to the anode of each LED string in the corresponding LED array. For example, the discharge port DIS1 is coupled to the anodes (eg, the common node N1 ) of each LED string in the first LED array A1 . The discharge port DIS2 is coupled to the anodes (eg, the common node N2 ) of each LED string in the second LED array A2 . 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 on each LED string in each LED array to be lower than a threshold (the threshold is called a conduction threshold). The conduction threshold is set so that no LED string will be conducted due to the peak current. The residual image removal module 501 includes a plurality of voltage adjustment units, such as voltage adjustment units 511-514 as an example. The number of voltage regulating 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 511-514 can be individually enabled or disabled by a corresponding enable signal. For example, the adjustment unit 511 can be controlled by the enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (shown in FIG. 5 ). The voltage adjustment units 511-514 are correspondingly coupled to the plurality of discharge ports DIS1-DIS4, respectively. 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 keep it below the threshold.

FIG. 6 shows the voltage regulation unit 511 in the controller 580 according to an embodiment of the present invention. In the embodiment shown in FIG. 6 , the voltage regulation unit 511 includes an amplifier 601 and a discharge switch 602 . The discharge switch 602 is coupled between the 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 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 make it follow the first voltage signal V1, thereby reducing the voltage of the first LED in the first LED array A1. voltage across the string to keep it below the turn-on threshold.

FIG. 7 shows the voltage adjustment unit 511 in the controller 580 according to an embodiment of the present invention. In the embodiment shown in FIG. 7 , 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 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 the discharge from the anode of the first LED string in the first LED array A1. The discharge current flowing from the switch 702 to the ground further reduces the voltage on the first LED string in the first LED array A1 to be lower than the conduction threshold.

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

FIG. 9 shows the voltage adjustment unit 511 in the controller 580 according to an embodiment of the present invention. In the embodiment shown in FIG. 9 , 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. The 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 the discharge current flowing from the anode of the first LED string in the first LED array A1 to the ground through the first branch, thereby reducing the current on the first LED string in the first LED array A1 voltage to keep it below the turn-on threshold.

Continuing to refer to FIG. 5 , according to different timing schemes, the voltage adjustment unit 511 can be enabled when the enable signal EN1 is at a first level (for example, logic high), or when the enable signal EN1 is at a second level (for example, logic high). logic low), the voltage regulation unit 511 is disabled. In one embodiment, the voltage adjustment unit 511 can be enabled all the time. In another embodiment, as shown in FIG. 10 , when the first switch SW1 is turned off, the voltage adjusting unit 511 can be enabled. In another embodiment, as shown in FIG. 11 , the voltage regulation unit 511 may be enabled in the time interval sequence BBM. The sequence of time intervals BBM is the interval between sequences of four discrete time slots in which switches SW1-SW4 are turned on exclusively. In other words, in each interval of the time interval sequence BBM, none of the switches SW1 - SW4 is turned on, and the voltage regulation unit 511 is enabled at the same time.

FIG. 12 shows a light source driving circuit 1200 including a controller 1280 for controlling a light source module according to an embodiment of the present invention. Components with the same reference numbers 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 cancellation module 1201 coupled to the decoding module 160 . The residual image removal 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 so that no LED string will be conducted due to the peak 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 regulating 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 by a corresponding enable signal. For example, the adjustment unit 1211 can be controlled by the enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (shown in FIG. 5 ). The voltage regulation units 1211-1214 are coupled to a power port VLEDIN and a plurality of current sensing ports ISEN1-ISEN8. Specifically, the voltage adjustment 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. voltage to keep it below the threshold.

FIG. 13 shows the voltage regulation unit 1211 in the 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 noninverting input terminal of the amplifier 1301 receives the third voltage signal V3 , the inverting input terminal of the amplifier 1301 is coupled to the current sensing port ISEN1 , and the output terminal of the amplifier 1301 is coupled to the charging 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 so that it follows the third voltage signal V3, thereby reducing the voltage of the first LED in the first LED array A1. voltage across the string to keep it below the turn-on threshold.

FIG. 14 shows the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In the embodiment shown in FIG. 14 , the voltage regulation unit 1211 includes a comparator 1401 and a charging switch 1402 . The charging switch 1402 is coupled between the power port VLEDIN and the current sensing port ISEN1. The noninverting input terminal of the comparator 1401 receives the fourth voltage signal V4 , the inverting input terminal of the comparator 1401 is coupled to the current sensing port ISEN1 , and the output terminal 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 conduct the flow from the power port VLEDIN to the first LED array through the charging switch 1402. The charging current of the cathode of the first LED string in A1 further reduces the voltage on the first LED string in the first LED array A1 to be lower than the conduction threshold.

FIG. 15 shows the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In the embodiment shown in FIG. 15 , the voltage regulation unit 1211 includes a charging switch 1502 . The charging switch 1502 is coupled between the power port VLEDIN and the current sensing port ISEN1. When the enable signal EN1 is turned on, the charging switch 1502 turns on the charging current flowing from the power port VLEDIN to the cathode of the first LED string in the first LED array A1, thereby reducing the charging current of the first LED string in the first LED array A1. the voltage on to keep it below the turn-on threshold.

FIG. 16 shows the voltage regulation unit 1211 in the controller 1280 according to an embodiment of the present invention. In the embodiment shown in FIG. 16 , the voltage regulation unit 1211 includes a current mirror 1601 . The first branch of the current mirror 1601 is coupled between the power port VLEDIN and the current sense port ISEN1 , and the 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 the enable signal EN1. When enabled, the current mirror 1601 conducts the charging current flowing from the power port VLEDIN to the cathode of the first LED string in the first LED array A1 through the first branch, thereby reducing the charging current of the first LED string in the first LED array A1. the voltage on to keep it below the turn-on threshold.

Continuing to refer to FIG. 12 , according to different timing schemes, the voltage adjustment unit 1211 can be enabled when the enable signal EN1 is at a first level (for example, logic high), or when the enable signal EN1 is at a second level (for example, logic high). logic low), the voltage regulation unit 1211 is disabled. In one embodiment, as shown in FIG. 17 , the voltage regulation unit 1211 can be enabled in the time interval sequence BBM. The sequence of time intervals BBM is the interval between sequences of four discrete time slots in which switches SW1-SW4 are turned on exclusively. In other words, in each interval of the time interval sequence BBM, none of the switches SW1 - SW4 is turned on, and the voltage regulation unit 1211 is enabled at the same time. In another embodiment, as shown in FIG. 18 , the voltage regulation unit 1211 can be enabled in the time interval sequence BBM, and if the corresponding control signal PWM1 (as shown in FIG. 2 ) is in the second state (eg, logic low), the voltage regulation unit 1211 can also be enabled.

FIG. 19 shows a light source driving circuit 1900 including a controller 1980 for controlling a light source module according to an embodiment of the present invention. Components with the same reference numbers as in FIG. 4 have similar functions. In the embodiment shown in FIG. 19, the controller 1980 includes a plurality of discharge ports DIS1-DIS4, each of which is coupled to the anode of each LED string in a corresponding LED array. For example, the discharge port DIS1 is coupled to the anodes (eg, the common node N1 ) of each LED string in the first LED array A1 . The discharge port DIS2 is coupled to the anodes (eg, the common node N2 ) of each LED string in the second LED array A2 . The controller 1980 includes a residual image removal module 1901 . The residual image elimination module 1901 is coupled to the decoding module 160 and is used for adjusting the voltage on each LED string in each LED array to be lower than the conduction threshold. The conduction threshold is set so that no LED string will be conducted due to the peak current. The residual image removal module 1901 includes a plurality of voltage regulation units, such as voltage regulation units 1911-1914 as an example. The number of voltage regulating 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 1911-1914 can be individually enabled or disabled by a corresponding enable signal. For example, the voltage adjustment unit 1911 can be controlled by an enable signal EN1. The enable signal EN1 is generated by the decoding module 160 (shown in FIG. 5 ). The voltage regulating 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 keep it below the turn-on threshold.

FIG. 20 shows the voltage adjustment unit 1911 in the controller 1980 according to one embodiment of the present invention. In the embodiment shown in FIG. 20 , the voltage adjustment unit 1911 includes a switch 2002 . The switch 2002 is coupled between the discharging port DIS1 and the current sensing port ISEN1. When the enable signal EN1 is turned on, the switch 2002 turns on 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 current of the first LED The voltage on the first LED string in array A1 is such that it is lower than the turn-on threshold.

FIG. 21 shows the voltage regulation unit 1911 in the controller 1980 according to one embodiment of the present invention. In the embodiment shown in FIG. 21 , the voltage regulation unit 1911 includes a current mirror 2101 . The first branch of the current mirror 2101 is coupled between the discharge port DIS1 and the current sensing port ISEN1 , and the 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 the 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 to the cathode of the first LED string in the first LED array A1 through the first branch, thereby reducing the first The voltage on the first LED string in the LED array A1 is made to be lower than the turn-on threshold.

Continuing to refer to FIG. 19 , according to different timing schemes, the voltage adjustment unit 1911 can be enabled when the enable signal EN1 is at a first level (for example, logic high), or when the enable signal EN1 is at a second level (for example, logic high). logic low), the voltage regulation unit 1911 is disabled. In one embodiment, as shown in FIG. 22 , when the first switch SW1 is turned off, the voltage adjusting unit 1911 can be enabled. In another embodiment, as shown in FIG. 23 , the voltage regulation unit 1911 may be enabled in the time interval sequence BBM. The sequence of time intervals BBM is the interval between sequences of four discrete time slots in which switches SW1-SW4 are turned on exclusively. In other words, in each interval of the time interval sequence BBM, none of the switches SW1 - SW4 is turned on, and the voltage regulation unit 1911 is enabled at the same time.

FIG. 24 shows a light source driving circuit 2400 including a controller 1980 for controlling a light source module according to an embodiment of the present invention. Components with the same reference numbers 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 a power supply (for example, coupled to the power converter 120 through a port PWIN). Each of the plurality of discharge ports DIS1-DIS4 is coupled to a corresponding common node among the common nodes N1-N4 through an NMOS transistor. Wherein, the gate of the NMOS transistor is also coupled to the power supply (for example, coupled to the power converter 120 through the port PWIN). With such a structure, the controller 1980 can work with the light source module whose input voltage VLED exceeds the tolerance voltage of the controller 1980 . Similar structures are also applicable to the controller 580 shown in FIG. 5 and the controller 1280 shown in FIG. 12 .

As mentioned 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 on the LED string to make it lower than the conduction threshold. Therefore, the LED string cannot be unintentionally illuminated, thereby eliminating the phenomenon of residual image on the display device.

The above detailed description and drawings are only typical embodiments of the present invention. Obviously, various additions, modifications and substitutions are possible without departing from the spirit and scope of the invention defined by the claims. Those skilled in the art should understand that the present invention may vary in form, structure, layout, proportion, material, elements, components and other aspects in actual application according to specific environment and work requirements without departing from the principle of the invention. Accordingly, the embodiments disclosed herein are intended to be illustrative and not limiting, with the scope of the invention being defined by the appended claims and their legal equivalents rather than by the foregoing description.

Claims (25)

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

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.

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