Light source driving system and light source driving apparatus

Abstract

The invention discloses a light source driving system and a light source driving device, which are used for driving a plurality of groups of light emitting diodes (LEDs) sharing one power supply end. In the system, a feedback node is used for generating a power supply adjusting signal to adjust a power supply voltage generated by a power supply on a power supply end. A plurality of light source driving devices connected with the feedback node are used for generating a plurality of feedback output signals so as to control the power supply adjusting signals in parallel. Wherein each light source driving device in the plurality of light source driving devices is used for driving a corresponding group of LEDs in the plurality of groups of LEDs, and generating a corresponding feedback output signal in the plurality of feedback output signals according to the power supply state of the corresponding group of LEDs. According to the light source driving system, power consumption can be reduced, working efficiency can be improved, and the response speed of adjusting the power supply voltage can be increased.

Description

Technical Field

[0001] The present invention relates to the field of light source driving, and in particular to a light source driving system and a light source driving device applied in an active matrix structure. Background Art

[0002] Figure 1 FIG. 1 is a block diagram of a light source driving system 100 for driving a backlight lamp with an active matrix structure in the prior art. Figure 1 As shown, the light source driving system 100 includes a power converter 102, a controller 104, and a plurality of light source driving devices 106_1-106_n (n is a natural number). The power converter 102 generates a supply voltage V LED The light source 108 is powered. The light source 108 includes a plurality of light emitting diode (LED) strings. The light source driving devices 106_1-106_n respectively drive the LED strings S11-S14, S21-S24, ..., Sn1-Sn4 in the light source 108 to adjust the current I on each LED string in the LED strings S11-S14, S21-S24, ..., Sn1-Sn4. LED to their respective target current values ​​I LED_TARGET The controller 104 provides the target current value I for the light source driving devices 106_1-106_n. LED_TARGET In addition, the controller 104 can look up the table LT (V LED_TARGET ,I LED_TARGET ) to search for the target current value I LED_TARGET Matching target voltage value V LED_TARGET , and provides a target voltage value V for the power converter 102 LED_TARGET The information enables the power converter 102 to control the supply voltage V LED is the target voltage value V LED_TARGET .

[0003] However, in most cases, the target voltage value V recorded in the lookup table LED_TARGET is greater than the actual supply voltage required by the light source 108. This is because when the light source 108 is at different temperatures, the current I in the LED strings S11-S14, S21-S24, ..., Sn1-Sn4 is adjusted. LED To the target current value I LED_TARGET To ensure that the light source 108 can receive sufficient power supply voltage within the normal operating temperature range (eg, -25°C to 85°C), the target voltage value V LED_TARGETThe value of is generally the maximum value of the power supply voltage required by the light source 108 within the normal operating temperature range. For example, when the light source 108 is at -25°C, the light source 108 needs to receive a power supply voltage V of at least 40V. LED In order to make its current I LED is adjusted to the target current value I LED_TARGET When the light source 108 is at 85°C, the light source 108 needs to receive a supply voltage V of at least 30V. LED In order to make its current I LED is adjusted to the target current value I LED_TARGET Or, when the light source 108 is at 20°C, the light source 108 needs to receive a supply voltage V of at least 35V. LED In order to make its current I LED is adjusted to the target current value I LED_TARGET In this example, the target voltage value V LED_TARGET The value of is 40 V or higher. This leads to a waste of electric energy, increases the power consumption of the light source driving system 100, and reduces the working efficiency of the light source driving system 100.

[0004] An existing solution includes using the controller 102 to read data from the driving devices 106_1-106_n, performing calculations based on the read data, and then controlling the power converter 102 based on the calculation results to adjust the supply voltage V LED In such a light source driving system, the driving devices 106_1-106_n need to be matched with a specific controller or processor (eg, MCU, microcontroller) to realize the control of the power converter 102. This reduces the compatibility and flexibility of the system. In addition, MCU is relatively expensive and consumes a lot of power.

[0005] In addition, if the area of ​​the backlight is large, a large number of LED strings are required, and therefore a correspondingly large number of light source driving devices are also required. In the existing light source driving system 100, a controller 104 receives status information of a string of light source driving devices 106_1-106_n to control the string of light source driving devices. If the light source driving system includes multiple strings of light source driving devices, multiple controllers are required to monitor and control the multiple strings of light source driving devices respectively. This will further increase the cost of the system.

[0006] In addition, in some specific cases, such as when the display is operating in high dynamic range mode (HDR mode), some areas of the display (for example, named area 1) need to be brighter than other areas (for example, named area 2). In other words, the current flowing through the LED in area 1 is greater than the current flowing through the LED in area 2, so the operating temperature of the light source driving device used to drive the LED in area 1 is higher than the operating temperature of the light source driving device used to drive the LED in area 2. Since the existing light source driving device has a built-in temperature protection module, when the light source driving device detects that its operating temperature is higher than the temperature protection threshold, the light source driving device will automatically shut down, and the corresponding multiple strings of LEDs will also be powered off, which will cause black areas to appear on the display, seriously affecting the visual effect. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide one or more solutions for at least solving the problems of high power consumption and low working efficiency in existing light source driving systems, and reducing the cost of light source driving systems for driving a large number of LEDs.

[0008] To solve the above technical problems, the present invention provides a light source driving system for driving multiple groups of LEDs sharing a common power supply end, comprising: a feedback node, configured to generate a power supply adjustment signal to adjust the power supply voltage generated by a power supply at the power supply end; and multiple light source driving devices connected to the feedback node, configured to generate multiple feedback output signals to control the power supply adjustment signals in parallel, wherein each of the multiple light source driving devices is configured to drive a corresponding group of LEDs among the multiple groups of LEDs, and generate a corresponding one of the multiple feedback output signals according to the power supply status of the corresponding group of LEDs.

[0009] The present invention also provides a light source driving device, comprising: a sensing end, configured to sense the power supply state of a first group of LEDs driven by the light source driving device, wherein the power supply state of the first group of LEDs includes a sufficient power supply state and an increaseable power supply state; a serial communication end, configured to communicate serially with a first adjacent driving device; a feedback input end, configured to receive a feedback input voltage from the first adjacent driving device, wherein the feedback input voltage indicates the power supply state of a second group of LEDs driven by the first adjacent driving device; a feedback output end, configured to provide a feedback output signal to adjust the power supply voltage of the first group of LEDs and the second group of LEDs; and a serial communication end, configured to communicate serially with a first adjacent driving device. The control circuit connected to the sensing end, the feedback input end and the feedback output end is configured to generate an internal voltage according to the power supply status of the first group of LEDs, select a feedback voltage between the internal voltage and the feedback input voltage, and generate the feedback output signal according to the feedback voltage. The control circuit is also configured to operate in one of a voltage feedback mode and a current feedback mode according to the application environment of the light source driving device, wherein in the voltage feedback mode, the feedback output signal includes a feedback output voltage controlled by the feedback voltage, and in the current feedback mode, the feedback output signal includes a feedback output current controlled by the feedback voltage.

[0010] By utilizing the light source driving system provided by the present invention, multiple light source driving devices can control the power supply adjustment signal on the feedback node in parallel according to the real-time power supply status of the LEDs driven by each of them to control all LEDs in the system to be in a state of sufficient power supply, thereby avoiding the waste of electric energy caused by using a lookup table to determine the light source power supply voltage in the prior art, thereby reducing the power consumption of the light source driving system and improving the working efficiency of the light source driving system. In addition, by utilizing the light source driving system provided by the present invention, it is possible to dynamically adjust the power supply voltage according to the actual power supply demand of the light source without using an MCU, thereby saving the cost of the system and further reducing the power consumption. In addition, since the adjustment of the power supply adjustment signal by the multiple light source driving devices is performed in parallel, the response speed and working efficiency of the system can be further improved.

[0011] By using the light source driving device provided by the present invention, the light source driving device can be selectively set to work in a voltage feedback mode or a current feedback mode according to the application environment in which the light source driving device is located (for example, a member of a series device or a member of a parallel device), thereby realizing a light source driving system with a series-parallel combination architecture. The light source driving system realized by the light source driving device provided by the present invention can monitor multiple strings of light source driving devices without using multiple controllers, thereby reducing the cost of the light source driving system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following description of some embodiments of the present invention in conjunction with the accompanying drawings may further provide an understanding of the objectives, specific structural features and advantages of the present invention.

[0013] Figure 1 Shown is a module schematic diagram of a light source driving system in the prior art.

[0014] Figure 2 FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0015] Figure 2A FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0016] Figure 2B FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0017] Figure 3A FIG. 1 is a module schematic diagram of a light source driving device according to an embodiment of the present invention.

[0018] Figure 3B FIG. 1 is a module schematic diagram of a light source driving device according to an embodiment of the present invention.

[0019] Figure 4 FIG. 1 is a circuit diagram of a comparison circuit and a power supply adjustment module according to an embodiment of the present invention.

[0020] Figure 5 FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0021] Figure 5A FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0022] Figure 6 FIG. 1 is a module schematic diagram of a light source driving device according to an embodiment of the present invention.

[0023] Fig. 6A FIG. 1 is a module schematic diagram of a light source driving device according to an embodiment of the present invention.

[0024] Figure 6B FIG. 1 is a circuit diagram of a comparison circuit and a power supply adjustment module according to an embodiment of the present invention.

[0025] Figure 7 FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention.

[0026] Figure 8 FIG. 1 is a module schematic diagram of a light source driving device according to an embodiment of the present invention.

[0027] Fig. 8A FIG. 1 is a circuit diagram of a comparison circuit and a power supply adjustment module according to an embodiment of the present invention.

[0028] Figure 8B FIG. 1 is a circuit diagram of a comparison circuit and a power supply adjustment module according to an embodiment of the present invention.

[0029] Fig. 9 FIG. 1 is a module schematic diagram of a light source driving system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will provide detailed reference to embodiments of the present invention. Although the present invention is described and illustrated by these embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, the present invention encompasses all substitutes, variants and equivalents within the spirit of the invention and the scope of the invention as defined by the appended claims.

[0031] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It will be appreciated by those skilled in the art that the present invention can be implemented without these specific details. In other examples, well-known methods, procedures, components and circuits are not described in detail in order to highlight the subject matter of the present invention.

[0032] The term "including" and its variations used in this document represent open inclusion, that is, "including but not limited to". The term "according to" or "based on" means "at least in part according to" or "based on at least in part". The term "one embodiment" means "at least one embodiment". The terms "first", "second", etc. may refer to different or identical samples. The terms "connected" or "coupled" may mean "direct electrical connection", "indirect electrical connection", or "coupled connection". The terms "a group" or "a string" may mean one or more. The term "proportional relationship" may include a linear proportional relationship, an exponential proportional relationship, and the like. For example, a positive proportional relationship between parameter A and parameter B may mean that parameter A increases as parameter B increases, and decreases as parameter B decreases; a negative proportional relationship between parameter A and parameter B may mean that parameter A decreases as parameter B increases, and increases as parameter B decreases.

[0033] The embodiment of the present invention provides a light source driving system with an active matrix structure. The light source driving system can be used to drive the light emitting diode (LED) in the display backlight. More specifically, the backlight can be composed of multiple groups of LEDs, each group of LEDs includes multiple strings of LEDs, and each string of LEDs includes one or more LEDs. In the embodiment of the present invention, the light source driving system includes multiple light source driving devices (or multiple strings of light source driving devices), and each light source driving device can drive a group of LEDs. The multiple light source driving devices (or multiple strings of light source driving devices) can adjust the power supply voltage of the backlight in parallel, and the adjustment is performed based on the real-time power supply status of the backlight. Compared with the light source driving system 100 in the prior art, the light source driving system of the embodiment of the present invention avoids the waste of electric energy caused by using a lookup table to determine the light source power supply voltage, reduces the power consumption of the light source driving system, improves the working efficiency of the light source driving system, and improves the adjustment speed of the power supply voltage of the backlight. In addition, in some embodiments of the present invention, the light source driving system can dynamically adjust its power supply voltage based on the real-time power supply demand of the backlight without using a specific controller or processor (e.g., MCU), thereby saving system costs and further reducing power consumption. Based on the test results, it can be seen that compared with some existing light source driving systems, the performance per watt of the light source driving system in the embodiment of the present invention can be improved by 5% to 10%.

[0034] In addition, the light source driving devices in some embodiments of the present invention can be configured to work in a voltage feedback mode or a current feedback mode according to the application environment in which they are located, so that some light source driving devices use the voltage feedback mode for serial feedback, and other light source driving devices use the current feedback mode for parallel feedback. Compared with the existing light source driving, the light source driving system composed of these light source driving devices can reduce costs and relatively quickly adjust all LEDs in the backlight.

[0035] In addition, in addition to the temperature protection function, the light source driving device in the embodiment of the present invention can also perform a thermal foldback function. Specifically, the temperature protection function means that when the light source driving device detects that its temperature is greater than the temperature protection threshold, the light source driving device can automatically shut down. The thermal foldback function can be enabled and disabled. After the thermal foldback function is enabled, if the light source driving device detects that its temperature is greater than the thermal foldback threshold (for example, called the first temperature threshold), the light source driving device can cool down by reducing the LED driving current. The light source driving device can reduce the LED driving current step by step until the temperature of the light source driving device is reduced to the second temperature threshold. Among them, the second temperature threshold is less than the first temperature threshold, and the first temperature threshold is less than the temperature protection threshold. Therefore, the display driven by the light source driving device in the embodiment of the present invention can avoid the black area phenomenon caused by excessive temperature.

[0036] Figure 2 The module schematic diagram of a light source driving system 200 according to an embodiment of the present invention is shown. The light source driving system 200 can drive multiple groups of LEDs S11-S1k, S21-S2k, ..., Sn1-Snk that share a power supply terminal 212. Wherein, k and n are both natural numbers. That is, LEDs S11-S1k, S21-S2k, ..., Sn1-Snk include n groups of LEDs, and each group of LEDs includes k strings of LEDs. Wherein, each string of LEDs includes one or more LEDs. In some embodiments, a string of LEDs may also be referred to as a group of LEDs.

[0037] like Figure 2 As shown, the light source driving system 200 includes a power source 202 (e.g., a DC / DC converter, an AC / DC converter, or other similar power converters), a feedback circuit 204, and a plurality of light source driving devices 206_1-206_n. Each light source driving device 206_1-206_n is configured to drive a corresponding group of LEDs among LEDs S11-S1k, S21-S2k, ..., Sn1-Snk. For example, the light source driving device 206_1 drives LEDs S11-S1k, the light source driving device 206_2 drives LEDs S21-S2k, and so on.

[0038] The light source driving devices 206_1-206_n are connected to the feedback node 240 and are configured to generate a plurality of feedback output signals 26_1-26_n so as to control the power supply regulation signal on the feedback node 240 in parallel. More specifically, each of the light source driving devices 206_1-206_n includes a plurality of sensing terminals IS1-ISk. Each sensing terminal IS1-ISk is configured to sense the voltage on the cathode of a corresponding string (or a group) of LEDs so as to sense the power supply state of the corresponding string (or a group) of LEDs. For example, the sensing terminal IS1 of the light source driving device 206_1 is connected to the cathode of the LED string S11 and can sense the voltage on the cathode, the sensing terminal IS2 of the light source driving device 206_1 is connected to the cathode of the LED string S12 and can sense the voltage on the cathode, and so on. In one embodiment, the voltage on the cathode of each string of LEDs can indicate the power supply state or current state of the string of LEDs. For example, if a string of LEDs is underpowered, the voltage on its cathode will be less than a specific voltage threshold, and the driving current on the string of LEDs cannot be adjusted to the target value. If the voltage on the cathode is greater than the specific voltage threshold, it can be determined that the string of LEDs is adequately powered, and the driving current on the string of LEDs can be adjusted to the target value. In one embodiment, the light source driving device 206_1 senses the voltage V on the terminals IS1-ISk. IS1 To V ISk (or collectively referred to as V IS ) and the preset voltage ADD_TH (for example: Figure 3A The preset voltage ADD_TH can be set to be equal to or slightly greater than the above voltage threshold. IS1 When the voltage V on the sensing terminal IS1 is greater than the preset voltage ADD_TH, the LED string (or: group) S11 is in a state of sufficient power supply. IS1 When the voltage V on the sensing terminals IS1-ISk is less than the preset voltage ADD_TH, the LED string (or: group) S11 is in a power-increasing state. IS When the voltages of at least one of the sensing terminals IS1-ISk are less than the preset voltage ADD_TH, the LED groups S11-S1k are considered to be in a state of sufficient power supply. When the voltages of at least one of the sensing terminals IS1-ISk are less than the preset voltage ADD_TH, the LED groups S11-S1k are considered to be in a state of increased power supply. The light source driving device 206_1 can generate a feedback output signal 26_1 (at Figure 2 In the example, the feedback output signal 26_1 includes the feedback output current I ADJFO1 Similarly, the light source driving devices 206_2-206_n may generate feedback output signals 26_2-26_n (eg, including feedback output current IADJFO2 to I ADJFOn ) in a corresponding feedback output signal. The light source driving devices 206_1-206_n generate feedback output signals 26_1-26_n in parallel to control the power supply adjustment signal (eg, current signal I 240 ).exist Figure 2 In the example of 240 Including the current value I of the feedback output signal ADJFO1 to I ADJFOn Therefore, the feedback output signals 26_1-26_n can control the power supply adjustment signal I in parallel. 240 .

[0039] The feedback node 240 may be configured to generate a power regulation signal I 240 To adjust the supply voltage V generated by the power supply 202 at the supply terminal 212 LED More specifically, the light source driving system 200 includes a feedback circuit 204 connected to a power supply terminal 212 and a feedback node 240, and configured to generate a feedback signal according to a power supply voltage V LED and the power supply regulation signal I 240 Generates power supply feedback signal V FB The power supply 202 can adjust the power supply feedback signal V FB To the power supply reference value V REF (not shown in the figure) to adjust the supply voltage V LED This ensures that LEDs S11-S1k, S21-S2k, ..., Sn1-Snk are all in a state of sufficient power supply.

[0040] By way of example, the feedback circuit 204 may include a resistor divider. Figure 2 For example, the feedback circuit 204 includes resistors R1, R2 and R3. The power supply feedback signal V FB It can be given by the following formula: V FB =V LED *R3 / (R1+R2+R3)+f(I 240 ), where f(I 240 ) represents the power supply regulation current I 240 More specifically, in some embodiments, the feedback output current I ADJFO1 to I ADJFOn Each of the feedback nodes 240 includes a sink current (SinkCurrent) flowing from the feedback node 240 into the corresponding light source driving device, so the power supply regulation current I 240 Flowing out from the connection point 210 of resistors R1 and R2, f(I 240 ) is negative, and the electrical regulation current I 240 The increase in the power supply feedback signal VFB When any LED string among LEDs S11-S1k, S21-S2k, ..., Sn1-Snk is in a power-increasing state, its corresponding light source driving device can increase its corresponding current sink to increase the electrical regulation current I 240 , thereby reducing the power supply feedback signal V FB The power source 202 (eg, a DC / DC converter or an AC / DC converter) can convert the feedback signal V FB With power supply reference V REF is compared with the feedback signal V FB Greater than the power supply reference V REF When reducing the supply voltage V LED , or the feedback signal V FB Less than the power supply reference V REF When increasing the supply voltage V LED , so that the feedback signal V FB is regulated to the supply reference value V REF The final regulated supply voltage V LED LEDs S11-S1k, S21-S2k, ..., Sn1-Snk are all in a state of sufficient power supply. In other embodiments, the feedback output current I ADJFO1 to I ADJFOn Each of the light source driving devices includes a source current (Source Current) flowing from the corresponding light source driving device to the feedback node 240, so the power supply regulating current I 240 Flows into the connection point 210 of the resistors R1 and R2, f(I 240 ) is positive, and the electrically regulated current I 240 The reduction of the power supply feedback signal V FB When any LED string among LEDs S11-S1k, S21-S2k, ..., Sn1-Snk is in a power-increasing state, its corresponding light source driving device can reduce its corresponding source current to reduce the electrical regulation current I 240 , thereby reducing the power supply feedback signal V FB Similarly, by setting the feedback signal V FB Adjust to the power supply reference value V REF , the power supply 202 can control the supply voltage V LED This can ensure that LEDs S11-S1k, S21-S2k, ..., Sn1-Snk are all in a state of sufficient power supply.

[0041] Although in Figure 2For example, the feedback circuit 204 includes resistors R1, R2 and R3 connected in series, but the present invention is not limited thereto. In other embodiments, the feedback circuit 204 may include other types of circuit structures, such as two resistors connected in series, multiple resistors connected in series and parallel, and the like.

[0042] Figure 2A FIG. 2 is a schematic diagram of a module of a light source driving system 200A according to an embodiment of the present invention. Figure 2 right Figure 2A The light source driving system 200A is similar to the light source driving system 200, the difference being that the light source driving devices 206_1-206_n in the system 200A are connected via bipolar PNP junction transistors (PNP transistors for short). FB1 To P FBn Connected to feedback node 240. Figure 2A In the example of FIG. 1 , the feedback output signals 26_1 - 26_n include the sink current I flowing into the light source driving device 206_1 - 206_n. ADJFO1 to I ADJFOn . Sink current I ADJFO1 to I ADJFOn For transistor P FB1 To P FBn The base current (Base Current) controls the transistor P FB1 To P FBn The emitter current (Emitter Current) I E1 to I En Specifically, the emitter current and the base current of the transistor can be in direct proportion. The power supply adjustment signal I 240 The emitter current I E1 to I En Therefore, the light source driving devices 206_1-206_n can control the power supply adjustment signal I on the feedback node 240 in parallel. 240 .

[0043] Figure 2B FIG. 2 is a schematic diagram of a module of a light source driving system 200B according to an embodiment of the present invention. Figure 2 right Figure 2B The light source driving system 200B is similar to the light source driving system 200, and the difference is that the light source driving devices 206_1-206_n in the system 200B are connected through bipolar NPN junction transistors (Bipolar NPN Junction Transistors, referred to as: NPN transistors) N FB1 To N FBnConnected to feedback node 240. Figure 2B In the example of FIG. 1 , the feedback output signals 26_1 - 26_n include the source current I flowing from the light source driving device 206_1 - 206_n. ADJFO1 to I ADJFOn . Source current I ADJFO1 to I ADJFOn For transistor N FB1 To N FBn The base current (Base Current) controls the transistor N FB1 To N FBn Collector Current I C1 to I Cn Specifically, the collector current and the base current of the transistor can be in direct proportion. The power supply regulation signal I 240 The collector current I C1 to I Cn Therefore, the light source driving devices 206_1-206_n can control the power supply adjustment signal I on the feedback node 240 in parallel. 240 .

[0044] Figure 3A FIG. 2 is a schematic diagram of a module of a light source driving device 206A according to an embodiment of the present invention. The light source driving device 206A may be an embodiment of the light source driving devices 206_1-206_n described above. Figure 2 , Figure 2A and Figure 2B right Figure 3A Describe. Figure 3A As shown, the light source driving device 206A includes a protection module 314, a reference setting circuit 316, a comparison circuit 318, a power supply adjustment module 320, a signal generating circuit 322, and a current driving circuit 338A.

[0045] In one embodiment, the plurality of LED strings driven by the light source driving device 206A (not shown in FIG. Figure 3A ) through corresponding transistors (eg, MOS tubes) Q1 to Q k and the sensing resistor R S1 To R Sk For example, a string of LEDs corresponding to the sensing terminal IS1 is connected to the reference ground GND via transistor Q1 and sensing resistor R S1 Connected to the reference ground GND, a string of LEDs corresponding to the sensing terminal IS2 is connected via transistor Q2 and sensing resistor R S2 Connect to the reference ground GND, and so on. Operational amplifiers OP1 to OP k Respectively with the corresponding transistors Q1 to Q kOperational amplifier OP1 to OP k (e.g. ideal operational amplifier) ​​can receive the current regulation signal V IADJ (e.g. voltage signal), and controls the corresponding transistors Q1 to Q k The current regulation signal V IADJ Applied to the corresponding sense resistor R S1 To R Sk The LED string drive current I LED to the target value. The maximum instantaneous value refers to when the transistor Q1, Q2, ..., or Q k When turned on, the maximum instantaneous current value flowing through the corresponding LED string. For example, when the LED string corresponding to the sensing terminal IS1 is sufficiently powered, the transistor Q1 can make the resistor R S1 The voltage value on the current regulation signal V IADJ When the LED string corresponding to the sensing terminal IS1 is underpowered, the resistor R S1 The voltage value on the IADJ Therefore, the maximum instantaneous value of the LED string connected to the sensing terminal IS1 can be V IADJ / R S1 Similarly, the maximum instantaneous value of the LED string connected to the sensing terminal IS2 can be V IADJ / R S2 In some embodiments, transistors Q1 to Q k The light source driving device 206A can sense the current regulating devices Q1 to Q k The sensing voltage V IS1 To V ISK , to determine the power supply status of the LED driven by the light source driving device 206A.

[0046] The signal generating circuit 322 (eg, including a pulse width modulation signal generator) can generate pulse width modulation signals PWM1 to PWMk to enable and disable the operational amplifiers OP1 to OP k , and adjusts the driving current I flowing through the corresponding LED string by controlling the duty cycle of the pulse width modulation signal LED For example, the pulse width modulation signal PWM1 can enable and disable the operational amplifier OP1, and its duty cycle can control the driving current I of the LED string connected to the sensing terminal IS1. LED Average value; the pulse width modulation signal PWM2 can enable and disable the operational amplifier OP2, and its duty cycle can control the driving current I of the LED string connected to the sensing terminal IS2 LEDaverage; and so on.

[0047] In one embodiment, if the sensing voltage V on the sensing terminal IS1 is IS1 If the driving current I LED The maximum instantaneous value of cannot be adjusted to the target value, which means that the LED string is underpowered (for example: the supply voltage V LED If the light source driving device 206A detects that the sensing voltage on at least one of the sensing terminals IS1 to ISk is too low, the light source driving device 206A may output a feedback signal (eg, I ADJFO ) to increase the supply voltage V LED , thereby increasing these sense voltages.

[0048] More specifically, in one embodiment, the comparison circuit 318 can convert the sensing voltage V on the sensing terminals IS1-ISk into IS1 To V ISk The voltage ADJ_TH is compared with the preset voltage ADD_TH, and the comparison result is provided to the power supply adjustment module 320. The power supply adjustment module 320 can generate a feedback output signal (for example, I ADJFO ) and adjust the feedback output signal according to the comparison result, thereby adjusting the sensing voltage V IS1 To V ISk is greater than or equal to the preset voltage ADD_TH.

[0049] In one embodiment, the comparison circuit 318 may repeatedly perform the above comparison action based on a specific frequency F1. IS1 To V ISk When at least one of the voltages is less than the preset voltage ADD_TH, an add signal ADD (eg, a digital signal “1” or a digital signal “0”) is generated. IS1 To V ISk If at least one of the voltages is continuously less than the preset voltage ADD_TH, the comparison circuit 318 can repeatedly generate the add signal ADD. Each time the add signal ADD is detected, the power supply adjustment module 320 changes (eg, increases or decreases) the feedback output current I ADJFO A certain amount ΔI1 to instruct the power supply 202 to increase the supply voltage V LED When the sensing voltage V IS1 To V ISk When both are greater than or equal to the preset voltage ADD_TH, the comparison circuit 318 stops generating the add signal ADD. When the add signal ADD is not detected, the power supply adjustment module 320 can repeatedly change (eg, reduce or increase) the feedback output current I based on the specific frequency F2. ADJFOA certain amount ΔI2 to reduce the supply voltage V LED , until the power supply adjustment module 320 detects the add signal ADD again. In this way, the sensing voltage V IS1 To V ISk Around the preset voltage ADD_TH, power consumption can also be reduced, and the temperature of the light source driving device can be lowered.

[0050] In one embodiment, the light source driving device 206A includes a clock signal generator (eg, a high frequency oscillator) for generating a clock signal to control the operating frequency F of the light source driving device 206A. OP In some embodiments, the pulse width modulation signals PWM1 to PWMk may be based on the operating frequency F OP To generate, for example: the frequency of the pulse width modulation signal PWM1 to PWMk can be the operating frequency F OP Similarly, the frequency F1 and / or the frequency F2 may be one or more times of the operating frequency F OP one or more times of .

[0051] In one embodiment, the reference setting circuit 316 can generate a preset voltage ADD_TH. The reference setting circuit 316 can also generate the current adjustment signal V IADJ To adjust the driving current I of each LED string driven by the light source driving device 206A LED The protection module 314 can detect the temperature TEM of the light source driving device 206A. 206 , to protect the light source driving device 206A from overheating. For example, when the protection module 314 detects the temperature TEM 206 Greater than the temperature protection threshold T OV When the temperature protection signal OTP is activated, the protection module 314 may generate a temperature protection signal OTP. In response to the temperature protection signal OTP, the light source driving device 206A may disconnect the power supply of the LED string to protect the light source driving device 206A. In addition, the protection module 314 may also perform a thermal foldback function. When the thermal foldback function is activated, if the protection module 314 detects that the temperature TEM of the light source driving device 206A is 206 Greater than the first temperature threshold T THF1 , the protection module 314 may generate a warning signal OTP_ALERT. In response to the warning signal OTP_ALERT, the reference setting circuit 316 may reduce (eg, gradually reduce) the preset voltage ADD_TH and the current adjustment signal V IADJ To reduce the temperature TEM 206 When the protection module 314 detects the temperature TEM 206 Decrease to the second temperature threshold TTHF2 When the reference setting circuit 316 maintains the preset voltage ADD_TH and the current regulation signal V IADJ The second temperature threshold T THF Less than the first temperature threshold T THF1 , the first temperature threshold T THF1 Less than the temperature protection threshold T OV By utilizing the heat return function of the embodiment of the present invention, the display driven by the light source driving device can avoid the black area phenomenon caused by excessive temperature.

[0052] Although in Figure 3A In the example of FIG. 2 , the current driving circuit 338A in the light source driving device 206A includes a plurality of operational amplifiers OP1 to OP k , but the present invention is not limited thereto. In other embodiments, the current driving circuit may include other circuit structures. For example, Figure 3B FIG. 2 is a schematic diagram of a module of a light source driving device 206B according to another embodiment of the present invention. The light source driving device 206B may be an embodiment of the light source driving devices 206_1-206_n described above. Figure 2 , Figure 2A , Figure 2B and Figure 3A right Figure 3B Give a description.

[0053] Figure 3B The light source driving device 206B in Figure 3A The light source driving device 206B is similar to the light source driving device 206A in FIG. 1 , except that the current driving circuit 338B in the light source driving device 206B includes a current mirror. The light source driving device 206B also includes driving switches SW1-SWk connected between the current mirror 338B and the sensing terminals IS1-ISk. More specifically, Figure 3A As shown, the switch SW1 connected to the sensing terminal IS1 can be used to enable and disable the driving current I on the sensing terminal IS1. LED The switch SW2 connected to the sensing terminal IS2 can be used to allow and prohibit the driving current I on the sensing terminal IS2. LED Flows through, and so on. The current mirror 338B includes a reference path (eg, transistor Q REF The current path where it is located) and multiple output paths (for example: transistor Q O1 To Q Ok The current mirror 338B can receive a current regulation signal (eg, a current signal I ADJ ) and in its output path (transistor Q O1 To Q Ok The driving current I is generated on the current path where LED, thereby adjusting the drive current I LED The maximum instantaneous value to the target value (for example: with the current regulation signal I ADJ Similar to the light source driving device 206A, the transistor Q in the light source driving device 206B O1 To Q Ok It can be called a current regulating device. The light source driving device 206B can sense the current regulating device Q O1 To Q Ok The sensing voltage V IS1 To V ISK , to determine the power supply status of the LED driven by the light source driving device 206B. In one embodiment, when the switch SW1 is turned on, the voltage on the switch SW1 is relatively small and can be ignored. Therefore, the sensing voltage V IS1 Can be considered as a current regulating device Q O1 Similarly, when switches SW2-SWk are turned on, the sensing voltage V IS2 To V ISK Can be considered as a current regulating device Q O2 To Q Ok The pulse width modulation signals PWM1 to PWMk generated by the signal generating circuit 322 can respectively turn on and off the switches SW1-SWk. Therefore, the signal generating circuit 322 can adjust the corresponding driving current I by controlling the duty cycle of the pulse width modulation signals PWM1 to PWMk. LED For example, the signal PWM1 may control the average value of the driving current on the switch SW1, the signal PWM2 may control the average value of the driving current on the switch SW2, and so on.

[0054] Figure 4 FIG. 3 is a schematic diagram of a circuit of a comparison circuit 318 and a power supply adjustment module 320 according to an embodiment of the present invention. Figure 2 , Figure 2A , Figure 2B , Figure 3A and Figure 3B right Figure 4 In one embodiment, the comparison circuit 318 includes comparators CMP1 to CMP k and a logic circuit 426 (eg, an OR gate, a NOR gate, a NAND gate, or an AND gate). The power supply regulation module 320 includes a feedback regulation module 428 and a temperature reduction module 430 .

[0055] In one embodiment, comparators CMP1 to CMP k The sensing voltage V IS1 To V ISk is compared with the preset voltage ADD_TH, and after checking the sensing voltage VIS1 To V ISk When the voltage in is less than the preset voltage ADD_TH, the add signal ADD1, ADD2, ..., and / or ADDk is generated. Any of the add signals ADD1, ADD2, ..., and / or ADDk can cause the logic circuit 426 to generate the control signal S ADD (Also referred to as “add signal”). The feedback adjustment module 428 receives the add signal S ADD The feedback output current I can be changed (for example, increased or decreased) ADJFO The cooling module 430 can generate a control signal S based on the specific frequency F2. MINUS (Also called "minus signal"). ADD In the case of MINUS To change (e.g., reduce or increase) the feedback output current I ADJFO If the feedback adjustment module 428 detects the addition signal S ADD Sum and subtraction signal S MINUS , the feedback adjustment module 428 may ignore the subtraction signal S MINUS .

[0056] Although in the above embodiments, the feedback output signals 26_1 - 26_n include current signals, the present invention is not limited thereto. In other embodiments, the feedback output signals include voltage signals. Figure 5 FIG. 6 is a schematic diagram of a module of a light source driving system 600 according to another embodiment of the present invention. Figure 2 right Figure 5 Give a description. Figure 5 The light source driving devices 506_1-506_n in Figure 2 The light source driving devices 206_1-206_n in FIG. 5 are similar, but the difference is that each of the feedback output signals 56_1-56_n generated by the light source driving devices 506_1-506_n includes a feedback output voltage V ADJFO1 、V ADJFO2 , ..., or V ADJFOn The power regulation signal on the feedback node 240 includes a voltage signal V 240 , which can be controlled by the minimum voltage value of the feedback output signals 56_1 - 56_n.

[0057] like Figure 5 As shown, the light source driving system 500 includes feedback diodes D respectively connected between the light source driving devices 506_1-506_n and the feedback node 240. FB1 To D FBn In one embodiment, the feedback diode D FB1 To DFBn Can have the same forward voltage drop V FVD Therefore, the feedback diode D FB1 To D FBn The circuit composed of (can be called: combination circuit D FB1 -D FBn ) can select the smallest feedback output signal among the feedback output signals 56_1-56_n to turn on the feedback diode D FB1 To D FBn One or more feedback diodes in the circuit make the minimum feedback output signal control the supply regulation voltage V via the conducting feedback diode 240 For example, if the voltage V ADJFO1 is the feedback output voltage V ADJFO1 To V ADJFOn The minimum value of the feedback diode D FB1 can be turned on, and the voltage on the feedback node 240 can be V FVD +V ADJFO1 . Since the voltage V ADJFO1 is the feedback output voltage V ADJFO1 To V ADJFOn The minimum value among the other feedback diodes D FB2 To D FBn The voltage drop across them is less than their forward conduction voltage V FVD , and the other feedback diode D FB2 To D FBn No conduction. Similarly, if the voltage V ADJFO1 and V ADJFO2 Same as the feedback output voltage V ADJFO1 To V ADJFOn The minimum value of the feedback diode D FB1 and D FB2 Therefore, the minimum value among the feedback output signals 56_1-56_n can control the supply regulation voltage V on the feedback node 240. 240 In one embodiment, the light source driving devices 506_1-506_n can generate the feedback output voltage V in parallel. ADJFO1 To V ADJFOn , thereby controlling the supply regulation voltage V in parallel 240 .

[0058] In one embodiment, the feedback circuit 204 can be configured to generate a voltage V LED and supply regulation voltage V 240 Generates power supply feedback signal V FB .and Figure 2 Similar to the embodiment in FIG. , the power supply 202 can adjust the power supply feedback signal VFB To the power supply reference value V REF To adjust the supply voltage V LED This ensures that LEDs S11-S1k, S21-S2k, ..., Sn1-Snk are all in a state of sufficient power supply. Figure 5 For example, the feedback circuit 204 includes resistors R1, R2 and R3. The power supply feedback signal V FB It can be given by the following formula: V FB =V LED *R3 / (R1+R2+R3)-f(V 240 ), where f(V 240 ) represents the supply regulation voltage V 240 More specifically, in some embodiments, if the feedback diode D FB1 To D FBn If both are not conducting, f(V 240 ) is zero; if the feedback output voltage V ADJFO1 To V ADJFOn The minimum value V ADJFO_MIN At least one feedback diode is turned on, then f(V 240 ) can be changed with V ADJFO_MIN decreases and increases with V ADJFO_MIN increases and decreases. Therefore, if V ADJFO_MIN Reduce, can reduce the power supply feedback signal V FB value, thereby increasing the supply voltage V LED ; If V ADJFO_MIN Increase, can increase the power supply feedback signal V FB value, thereby reducing the supply voltage V LED .

[0059] In some embodiments, the feedback diode D FB1 To D FBn It can be any type of diode. For example, Figure 5 As shown, the feedback diode D FB1 To D FBn It can be a common diode. For example, Figure 5A As shown, the feedback diode D FB1 To D FBn It can be a metal oxide semiconductor field effect transistor (Metal-Oxide-Semiconductor Field-EffectTransistor, referred to as MOS tube) M FB1 To M FBn The body diode (Body Diode) in the Figure 5A In the example of MOS tube M FB1 To M FBnWhen both are disconnected, MOS tube M FB1 To M FBn The body diode in can perform similarly to the feedback diode D above. FB1 To D FBn In some possible embodiments, the MOS tube M FB1 To M FBn One of the MOS tubes is turned on, so that the feedback output voltage V ADJFO1 To V ADJFOn Select a voltage to control the supply voltage V LED .

[0060] Figure 6 FIG. 5 is a schematic diagram of a module of a light source driving device 506 according to an embodiment of the present invention. The light source driving device 506 may be an embodiment of the light source driving device 506_1-506_n described above. Figure 3A , Figure 3B , Figure 4 , Figure 5 and Figure 5A right Figure 6 Give a description. Figure 6 The light source driving device 506 in the embodiment can be connected with Figure 3A The light source driving device 206A or Figure 3B The light source driving device 206B in FIG. 5 is similar to the light source driving device 206B in FIG. 506 , except that the feedback output signal generated by the power supply adjustment module 620 in the light source driving device 506 includes the feedback output voltage V ADJFO The power supply adjustment module 620 adjusts the feedback output voltage V according to the result signal generated by the comparison circuit 318. ADJFO , thereby adjusting the sensing voltage V IS1 To V ISk is greater than or equal to the preset voltage ADD_TH.

[0061] For example, Figure 3A and Figure 3B The comparison circuit 318 and the power supply adjustment module 320 are similar. Figure 6 The comparison circuit 318 in the sensing terminal IS1-ISk can detect the sensing voltage V IS1 To V ISk The comparison circuit 318 compares the sense voltage V with the preset voltage ADD_TH and provides the comparison result to the power supply adjustment module 620. The comparison circuit 318 can repeatedly perform the above comparison action based on a specific frequency F1. IS1 To V ISk When at least one of the voltages is less than the preset voltage ADD_TH, an add signal ADD (eg, a digital signal “1” or a digital signal “0”) is generated. IS1 To VISk If at least one of the voltages is continuously less than the preset voltage ADD_TH, the comparison circuit 318 can repeatedly generate the add signal ADD. Each time the add signal ADD is detected, the power regulation module 620 changes (eg, reduces) the feedback output voltage V ADJFO A certain amount ΔV1 to instruct the power supply 202 to increase the supply voltage V LED When the sensing voltage V IS1 To V ISk When both are greater than or equal to the preset voltage ADD_TH, the comparison circuit 318 stops generating the add signal ADD. When the add signal ADD is not detected, the power supply adjustment module 620 can repeatedly change (eg, increase) the feedback output voltage V based on a specific frequency F2. ADJFO A certain amount ΔV2 to reduce the supply voltage V LED , until the power supply adjustment module 620 detects the add signal ADD again. In this way, the sensing voltage V IS1 To V ISk Around the preset voltage ADD_TH, power consumption can also be reduced, and the temperature of the light source driving device can be lowered.

[0062] Fig. 6A FIG. 5 is a block diagram of a light source driving device 506A according to another embodiment of the present invention. The light source driving device 506A may be an embodiment of the light source driving devices 506_1 - 506_n described above. Fig. 6A The light source driving device 506A and Figure 6 The light source driving device 506 in FIG. 1 is similar to the light source driving device 506 in FIG. 1 , except that the light source driving device 506A includes a feedback input terminal ADJFIN and a power supply adjustment module 620A. The power supply adjustment module 620A can receive power from an adjacent light source driving device (not in FIG. 1 ) at the feedback input terminal ADJFIN. Fig. 6A The feedback input voltage V ADJFIN . Feedback input voltage V ADJFIN The power supply adjustment module 620A also generates an internal voltage V according to the power supply status of the LED driven by the light source driving device 506A. ADJF (Not in Fig. 6A ), and the feedback input voltage V ADJFIN and the internal voltage V ADJF Select one (for example, a voltage with a smaller value) as the feedback output voltage V ADJFO , and outputs the feedback output voltage V at the feedback input terminal ADJFO ADJFO The feedback output voltage V ADJFOIt can indicate the power supply status of all LEDs driven by the above two light source driving devices. In addition, the light source driving device 506A includes a signal input terminal SDI and a signal output terminal SDO, which are used for input and output of signals (for example, including command signals, configuration information signals, data signals, etc.). More specifically, the signal terminals SDI and SDO can be serial communication terminals, which are configured to perform single-wire serial communication (1-Wire Communication) with the above adjacent light source driving devices. Therefore, the light source driving device 506A can perform single-wire serial communication with other light source driving devices through the signal terminals SDI and SDO, and transmit the information of the status of all LEDs driven by these light source driving circuits to the above feedback circuit 204 through the signal terminals ADJFIN and ADJFO.

[0063] Figure 6B FIG. 6 is a circuit diagram of a comparison circuit 318 and a power supply adjustment module 620A according to an embodiment of the present invention. Figure 6B The power supply regulation module 620A and Figure 4 The power supply regulation module 620A is similar to the power supply regulation module 320 in FIG. 4 , except that the power supply regulation module 620A includes a feedback regulation module 628 and a selection circuit 636. The feedback regulation module 628 generates a feedback signal S according to the addition signal S provided by the logic circuit 426. ADD and the temperature reduction signal S provided by the temperature reduction module 430 MINUS To generate the internal voltage V ADJF For example, the feedback adjustment module 628 receives the plus signal S ADD When the internal voltage V ADJF A quantity ΔV1. When no plus signal S is detected ADD In the case of MINUS To increase the internal voltage V ADJF If the feedback adjustment module 628 detects the addition signal S ADD Sum and subtraction signal S MINUS , the feedback adjustment module 628 may ignore the subtraction signal S MINUS The selection circuit 636 is fed back to the input voltage V ADJFIN and the internal voltage V ADJF Select the smaller voltage as the feedback output voltage V ADJFO .

[0064] Figure 7 FIG. 7 is a schematic diagram of a module of a light source driving system 700 according to an embodiment of the present invention. Figure 5 , Fig. 6A and Figure 6B right Figure 7 Describe. Figure 7As shown, the light source driving system 700 includes multiple strings of light source driving devices 7(1)(1)-7(m)(1), 7(1)(2)-7(m)(2), ..., 7(1)(n)-7(m)(n). Among them, m and n are both natural numbers. That is to say, the multiple strings of light source driving devices include n strings of devices, and each string of devices includes m devices. In one embodiment, each device in the devices 7(1)(1)-5(m)(1), 7(1)(2)-5(m)(2), ..., 7(1)(n)-5(m)(n) (hereinafter referred to as device 7) is similar to the above-mentioned light source driving devices 506_1-506_n, the difference being that the device 7 also includes a synchronization input terminal SYNCIN, a synchronization output terminal SYNCO, and a feedback input terminal ADJFIN. In addition, the signal input terminal SDI and the signal output terminal SDO of the device 7 can be used for single-wire serial communication (1-Wire Communication). Therefore, the light source driving devices 7(1)(1)-7(m)(1) can perform single-line serial communication; the light source driving devices 7(1)(2)-7(m)(2) can perform single-line serial communication; and so on. In some embodiments, the device 7 may include Fig. 6A The circuit structure of the light source driving device 506A.

[0065] like Figure 7 As shown, the light source driving system 700 can drive multiple groups of LED strings that share a power supply terminal 212. Each device 7 can drive one group of LED strings in the multiple groups of LED strings. For example, device 7(1)(1) can drive LED string group 74(1), device 7(2)(1) can drive LED string group 74(2), and so on. Device strings 7(1)(1)-7(m)(1), 7(1)(2)-7(m)(2), ..., 7(1)(n)-7(m)(n) are respectively connected via feedback diodes D FB1 To D FBn Connected to feedback node 240. Each string of devices includes a master device and multiple slave devices, and the multiple slave devices can communicate serially with the master device. For example: device string 7(1)(1)-7(m)(1) includes master device 7(1)(1) and slave devices 7(2)(1)-7(m)(1), and slave devices 7(2)(1)-7(m)(1) can communicate serially with master device 7(1)(1); device string 7(1)(2)-7(m)(2) includes master device 7(1)(2) and slave devices 7(2)(2)-7(m)(2), and slave devices 7(2)(2)-7(m)(2) can communicate serially with master device 7(1)(2); and so on.

[0066] In one embodiment, the master device may output a feedback output signal (eg, Figure 7 The VADJFO1 、V ADJFO2 , ..., or V ADJFOn ), used to indicate the power supply status of multiple LED strings driven by the string device. Feedback diode D FB1 To D FBn The feedback output voltage V ADJFO1 To V ADJFOn Select the minimum voltage V ADJFO_MIN , and generates a supply regulation voltage V at the feedback node 240 240 , for example: V 240 =V FVD +V ADJFO_MIN , where V FVD Represents the feedback diode D FB1 To D FBn The power supply 202 adjusts the voltage V according to the power supply 240 Regulate the supply voltage V LED This ensures that all LED strings driven by the light source driving system 700 are adequately powered.

[0067] For example, Figure 7 As shown, the first slave device 7(2)(1) is connected adjacent to the master device 7(1)(1), and the second slave device 7(3)(1) (not in Figure 7 ) is connected adjacent to the first slave device 7(2)(1). The feedback input terminal ADJFIN of the first slave device 7(2)(1) can receive a feedback input voltage 744 from the feedback output terminal ADJFO of the second slave device 7(3)(1). The feedback input voltage 744 can indicate the power supply status of the LED string group 74(3)-74(m) driven by the slave device 7(3)(1)-7(m)(1). The feedback output terminal ADJFO of the first slave device 7(2)(1) provides a feedback output voltage 746 to the master device 7(1)(1) (or referred to as: master light source driving device). The first slave device 7(2)(1) may include a power supply adjustment module (for example: Fig. 6A Module 620A shown in FIG. 1 is used to generate a first internal voltage (e.g., Figure 6B The voltage V ADJF ), and from the first internal voltage V ADJF The smaller signal is selected from the feedback input signal 744 and the feedback output signal 746. Therefore, the feedback output signal 746 can indicate the power supply status of the LED string group 74 (2)-74 (m). Similarly, the master device 7 (1) (1) (or referred to as: the master light source driving device) generates a second internal voltage (for example: Figure 6B The voltage V ADJF), from the second internal voltage V ADJF and the feedback output signal 746 from the first slave device 7(2)(1) to select the smaller signal as the feedback output voltage V ADJFO1 Therefore, the feedback output voltage V ADJFO1 The power supply status of the LED string groups 74 (1)-74 (m) can be indicated. Similarly, the feedback output voltage V ADJFO2 It can indicate the power status of the LED string driven by device 7(1)(2)-7(m)(2), and so on. Feedback diode D FB1 To D FBn The feedback output voltage V ADJFO1 To V ADJFOn Select the minimum voltage V ADJFO_MIN The selected feedback output voltage V ADJFO_MIN The power supply status of all LED strings driven by the system 700 can be indicated (for example, whether there is an LED in a power-on state). Therefore, the power supply 702 can output the voltage V according to the feedback. ADJFO_MIN To adjust Figure 7 The supply voltage V of all LED strings in LED , so that all LED strings are adequately powered.

[0068] Figure 8 FIG. 8 is a schematic diagram of a module of a light source driving device 806 according to another embodiment of the present invention. Fig. 6A right Figure 8 Give a description. Figure 8 The light source driving device 806 in the embodiment can be used with Fig. 6A The light source driving device 806 is similar to the light source driving device 506A in FIG. 8 , except that the light source driving device 806 supports both the voltage feedback mode and the current feedback mode. More specifically, the power supply regulating module 820 in the light source driving device 806 includes a feedback regulating module 628, a cooling module 430, a selector 836, and a feedback output circuit 834. The output signal 842 of the feedback output circuit 834 can be configured as a feedback output voltage or a feedback output current according to the application environment in which the light source driving device 806 is located.

[0069] For example, the application environment includes a first environment and a second environment. If the feedback output terminal ADJFO of the light source driving device 806 provides a feedback output signal 842 to the feedback input terminal ADJFIN of the adjacent light source driving device, the light source driving device 806 is in the first environment, and the power supply adjustment module 820 is configured to operate in the voltage feedback mode. In the voltage feedback mode, the feedback output signal 842 includes a feedback output voltage. If the feedback output terminal ADJFO of the light source driving device 806 provides a feedback output signal 842 to the feedback input terminal ADJFIN for controlling the power supply voltage V LEDThe feedback circuit 204 of the light source driving device 806 provides a feedback output signal 842, then the light source driving device 806 is in the second environment, and the power supply regulating module 820 is configured to operate in the current feedback mode. In the voltage feedback mode, the feedback output signal 842 includes the feedback output current. In some embodiments, the light source driving device 806 can receive configuration information through the signal input terminal SDI, and set the power supply regulating module 820 to operate in the voltage feedback mode or the current feedback mode according to the configuration information.

[0070] Fig. 8A FIG. 8 is a schematic diagram of a circuit of a comparison circuit 318 and a power supply adjustment module 820A according to an embodiment of the present invention. Figure 6B and Figure 8 right Fig. 8A Give a description. Fig. 8A The power supply regulation module 820A in may be Figure 8 An embodiment of the power supply regulation module 820 in FIG. Fig. 8A The operation process of the comparison circuit 318, the feedback adjustment module 628, the cooling module 430 and the selector 836 in the embodiment is similar to the operation process of the comparison circuit 318, the feedback adjustment module 628, the cooling module 430 and the selection circuit 636 described above. The difference is that Fig. 8A The feedback voltage 824 generated by the selector 836 in the circuit 830 can control the feedback output signal 842 generated by the feedback output circuit 834. More specifically, the selector 836 can receive the feedback voltage V ADJFIN , receives the internal voltage V from the feedback regulation module 628 ADJF , and at voltage V ADJFIN and V ADJF The smaller voltage is selected as the feedback voltage 824. The feedback output circuit 834 generates a feedback output signal 842 according to the feedback voltage 824.

[0071] For example, Fig. 8A As shown, the feedback output circuit 834 includes a selector 856 and two paths connected between the selector 856 and the selector 836. One of the paths (hereinafter referred to as the first path) includes a voltage follower 848 (Voltage Follower); the other path (hereinafter referred to as the second path) includes a current mirror 850 (Curret Mirror), a voltage-to-current circuit connected to the first branch of the current mirror 850, and a sink current source 854 (Sink Current Source) connected to the second branch of the current mirror 850. The voltage-to-current circuit may include an operational amplifier 852, a transistor Q 852 and resistor R 852The current sink source 854 generates a current sink I 854 In the first path, the voltage follower 848 can adjust the value of the feedback voltage 824 (eg, V ADJFO ) is transferred to the selector 856. Therefore, the selector 856 can receive the feedback voltage V from the first path ADJFO On the second path, the voltage-to-current circuit converts the value of the feedback voltage 824 to V ADJFO Converted into the first current I 852 (Wherein, the first current I 852 With voltage V ADJFO In direct proportion to the first current I 852 Generate a second current I 850 (Wherein, the second current I 850 With the first current I 852 = 1 1 1 (in direct proportion to the current flowing into the current sink 854). Therefore, the selector 856 can also receive the feedback current I from the second path. ADJFO , where I ADJFO =I 854 -I 850 .exist Fig. 8A For example, the feedback current I ADJFO The current absorbed by the power supply regulation module 820A is the current absorbed by the power supply regulation module 820A, and its current value can be related to the voltage value V ADJFO If the power supply regulation module 820A is set to work in the voltage feedback mode, the selector 856 selects the voltage V ADJFO is the feedback output signal 842. If the power supply regulation module 820A is set to work in the current feedback mode, the selector 856 selects the sink current I ADJFO is the feedback output signal 842 .

[0072] Figure 8B FIG. 8 is a schematic diagram of a circuit of a comparison circuit 318 and a power supply adjustment module 820B according to another embodiment of the present invention. Figure 6B , Figure 8 and Fig. 8A right Figure 8B Give a description. Figure 8B The power supply regulation module 820B in the embodiment may be Figure 8 An embodiment of the power supply regulation module 820 in FIG. Figure 8B The power supply regulation module 820B and Fig. 8A The difference is that the feedback current I generated on the second path of the power supply regulation module 820B is similar to the power supply regulation module 820A in FIG. ADJFO The current value of the power supply regulating module 820B can be related to the voltage value V ADJFO In direct proportion.

[0073] Fig. 9 FIG. 9 is a schematic diagram of a module of a light source driving system 900 according to an embodiment of the present invention. Figure 7 , Figure 8 , Fig. 8A and Figure 8B right Fig. 9 Give a description. Fig. 9 The light source driving system 900 in Figure 7 The light source driving system 700 is similar to the light source driving system 700, except that the light source driving devices 9(1)(1)-9(m)(1), 9(1)(2)-9(m)(2), ... and 9(1)(n)-9(m)(n) in the light source driving system 900 can be set to operate in voltage feedback mode or current feedback mode according to their respective application environments. Figure 8 The light source driving device 806 may be Fig. 9 Embodiments of the light source driving devices 9(1)(1)-9(m)(1), 9(1)(2)-9(m)(2), ... and 9(1)(n)-9(m)(n).

[0074] For example, in some embodiments, compared with the current transmission circuit, the design of the voltage transmission circuit is simpler and has lower cost and power consumption. Therefore, the slave device string 9(2)(1)-9(m)(1) can be set to work in the voltage feedback mode, by each generating a feedback output voltage V ADJFO The power supply status information of the LED driven by the slave device string 9(2)(1)-9(m)(1) is transmitted to the master device 9(1)(1) in a manner. Similarly, the slave devices 9(2)(2)-9(m)(2) can also be set to voltage feedback mode, and so on. In addition, in some embodiments, compared with voltage parallel control, current parallel control has a faster response speed and higher control efficiency. Therefore, the master devices 9(1)(1), 9(1)(2), ..., 9(1)(n) can be set to operate in current feedback mode, by each generating a feedback output current I ADJFO1 to I ADJFOn In a manner, the power supply regulation signal I on the feedback node 240 is controlled in parallel. 240 .

[0075] Therefore, compared with the light source driving system in the prior art, the light source driving system 900 composed of the light source driving device 806 in the embodiment of the present invention does not need to use multiple controllers to monitor multiple strings of light source driving devices (i.e., reduce costs and power consumption), and can also achieve fast and effective control of the power supply voltage of the LED.

[0076] The words and expressions used herein are for illustration and not limitation. The use of these words and expressions does not exclude any equivalents (or partial equivalents) of the features illustrated and described herein from the scope of the invention. Various modifications are possible within the scope of the claims. Other modifications, variations and alternatives may also exist. Therefore, the claims are intended to cover all such equivalents.

Claims

1. A light source driving system for driving a plurality of LED groups sharing a power supply terminal, comprising: A feedback node configured to generate a power supply regulation signal to regulate a supply voltage generated by a power supply at the power supply end; as well as A plurality of light source driving devices connected to the feedback node are configured to generate a plurality of feedback output signals so as to control the power supply adjustment signal in parallel, wherein each of the plurality of light source driving devices is configured to drive a corresponding group of LEDs among the plurality of groups of LEDs, and to generate a corresponding one of the plurality of feedback output signals according to the power supply status of the corresponding group of LEDs.

2. The light source driving system according to claim 1, further comprising: A feedback circuit connected to the power supply end and the feedback node is configured to generate a power supply feedback signal according to the power supply voltage and the power supply adjustment signal, wherein the power supply adjusts the power supply voltage by adjusting the power supply feedback signal to a power supply reference value so that the multiple groups of LEDs are all in a state of sufficient power supply.

3. The light source driving system according to claim 1, characterized in that: Each feedback output signal of the plurality of feedback output signals comprises a feedback output voltage, and the supply regulation signal is controlled by a minimum voltage value of the plurality of feedback output signals.

4. The light source driving system according to claim 3, further comprising: A plurality of feedback diodes are respectively connected between the plurality of light source driving devices and the feedback node, and are used to select a minimum feedback output signal from the plurality of feedback output signals to turn on at least one feedback diode among the plurality of feedback diodes, so that the minimum feedback output signal controls the power supply adjustment signal via the turned-on feedback diode.

5. The light source driving system according to claim 1, characterized in that: Each of the plurality of feedback output signals includes a feedback output current flowing through the feedback node, and the supply regulation signal is controlled by a sum of current values ​​of the plurality of feedback output signals.

6. The light source driving system according to claim 5, characterized in that: The feedback output current includes a sink current flowing into a corresponding one of the plurality of light source driving devices.

7. The light source driving system according to claim 5, characterized in that: The feedback output current includes a source current flowing from a corresponding one of the plurality of light source driving devices.

8. The light source driving system according to claim 1, characterized in that: The power supply state includes a sufficient power supply state and an increaseable power supply state, wherein a first light source driving device among the multiple light source driving devices is configured to drive a first group of LEDs among the multiple groups of LEDs, and sense a sensing voltage on a current regulating device connected between the first group of LEDs and a reference ground, wherein when the sensing voltage is greater than a preset voltage, the first group of LEDs is in the sufficient power supply state, and wherein when the sensing voltage is less than the preset voltage, the first group of LEDs is in the increaseable power supply state.

9. The light source driving system according to claim 8, characterized in that: The first light source driving device comprises: a comparison circuit connected to the current regulating device, configured to compare the sensed voltage with the preset voltage; and The power supply adjustment module connected to the comparison circuit is configured to adjust the feedback output signal of the first light source driving device according to the comparison result, so as to adjust the sensing voltage to be greater than or equal to the preset voltage.

10. The light source driving system according to claim 9, characterized in that: The first light source driving device further includes: a reference setting circuit connected to the comparison circuit, configured to generate the preset voltage and generate a current adjustment signal to adjust the maximum instantaneous value of the driving current of the first group of LEDs; and A protection module connected to the reference setting circuit is configured to detect the temperature of the first light source driving device, wherein when the temperature is greater than a first temperature threshold, the reference setting circuit reduces the preset voltage and the current regulation signal to reduce the temperature, and when the temperature is reduced to a second temperature threshold, the reference setting circuit maintains the preset voltage and the current regulation signal unchanged, and wherein the second temperature threshold is less than the first temperature threshold.

11. The light source driving system according to claim 1, further comprising: A plurality of strings of slave devices, each string of the plurality of strings of slave devices includes a plurality of slave devices and is configured to perform serial communication with a light source driving device corresponding to one of the plurality of light source driving devices, wherein a first slave device of the plurality of slave devices connected adjacent to the corresponding light source driving device is configured to drive a first group of LEDs of the plurality of groups of LEDs, wherein the first slave device includes: a feedback input terminal configured to receive a feedback input voltage from a second slave device connected adjacent to the first slave device among the plurality of slave devices; A feedback output terminal, configured to provide a feedback output voltage to the corresponding light source driving device; a sensing end configured to sense a power supply state of the first group of LEDs; and A power supply regulating module connected to the feedback input terminal, the feedback output terminal and the sensing terminal is configured to generate a first internal voltage according to the power supply state of the first group of LEDs, and select the feedback output voltage from the first internal voltage and the feedback input voltage.

12. The light source driving system according to claim 11, characterized in that: The corresponding light source driving device is configured to generate a second internal voltage according to the power supply status of a group of LEDs driven by the corresponding light source driving device, and select a voltage from the second internal voltage and the feedback output voltage from the first slave device to control the feedback output signal of the corresponding light source driving device.

13. A light source driving device, comprising: A sensing end configured to sense a power supply state of a first group of LEDs driven by the light source driving device, wherein the power supply state of the first group of LEDs includes a sufficient power supply state and an increaseable power supply state; A serial communication terminal configured to communicate serially with a first adjacent drive device; a feedback input terminal configured to receive a feedback input voltage from the first adjacent driving device, wherein the feedback input voltage indicates a power supply state of a second group of LEDs driven by the first adjacent driving device; a feedback output terminal configured to provide a feedback output signal to adjust the supply voltage of the first group of LEDs and the second group of LEDs; and The control circuit connected to the sensing end, the feedback input end and the feedback output end is configured to generate an internal voltage according to the power supply status of the first group of LEDs, select a feedback voltage between the internal voltage and the feedback input voltage, and generate the feedback output signal according to the feedback voltage. The control circuit is also configured to operate in one of a voltage feedback mode and a current feedback mode according to the application environment of the light source driving device, wherein in the voltage feedback mode, the feedback output signal includes a feedback output voltage controlled by the feedback voltage, and in the current feedback mode, the feedback output signal includes a feedback output current controlled by the feedback voltage.

14. The light source driving device according to claim 13, characterized in that: The application environment includes a first environment and a second environment, wherein, if the feedback output terminal provides the feedback output signal to the feedback input terminal of a second adjacent driving device, the light source driving device is in the first environment, and the control circuit operates in the voltage feedback mode; if the feedback output terminal provides the feedback output signal to a feedback circuit for controlling the supply voltage, the light source driving device is in the second environment, and the control circuit operates in the current feedback mode.

15. The light source driving device according to claim 13, characterized in that: The sensing end is connected to the reference ground through a current regulating device, and the current regulating device is configured to control the current flowing through the first group of LEDs and the sensing end, wherein when the voltage on the sensing end is greater than a preset voltage, the first group of LEDs is in the sufficient power supply state, and when the voltage on the sensing end is less than the preset voltage, the first group of LEDs is in the power increaseable state.

16. The light source driving device according to claim 15, characterized in that: The control circuit comprises: a comparison circuit connected to the sensing end, configured to compare the voltage on the sensing end with the preset voltage; and The power supply regulating module connected to the comparison circuit, the feedback input terminal and the feedback output terminal is configured to generate the internal voltage according to the comparison result to regulate the voltage on the sensing terminal to be greater than or equal to the preset voltage.

17. The light source driving device according to claim 16, characterized in that: The control circuit further comprises: a reference setting circuit connected to the comparison circuit, configured to generate the preset voltage and generate a current adjustment signal to adjust the maximum instantaneous value of the driving current of the first group of LEDs; and A protection module connected to the reference setting circuit is configured to detect the temperature of the light source driving device, wherein when the temperature is greater than a first temperature threshold, the reference setting circuit reduces the preset voltage and the current regulation signal to reduce the temperature, and when the temperature is reduced to a second temperature threshold, the reference setting circuit maintains the preset voltage and the current regulation signal unchanged, and wherein the second temperature threshold is less than the first temperature threshold.

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