Circuit for driving LED matrix using equalizer sub-circuit and shared amplifier for controlling LED clusters in loop

Abstract

The present disclosure relates to a circuit for driving an LED matrix using equalizer sub-circuits and shared amplifiers for controlling LED clusters in a loop. In some examples, the present disclosure describes a method of controlling an N multiplied by M micro LED cluster, where N and M are positive integers. The method may include receiving, by an amplifier circuit, a reference voltage, and outputting, by the amplifier circuit, a regulated voltage to an equalizer sub-circuit. The method may also include outputting, by the equalizer sub-circuit, a regulated voltage to each of the NxM power stages, and driving, by the NxM power stages, the NxM micro-LEDs based on the regulated voltage.

Description

Technical Field

[0001] This disclosure relates to circuitry for driving and controlling pixelated light sources, such as circuitry for vehicle headlights that include a matrix of light-emitting diodes (LEDs) or other pixelated light sources. Background Technology

[0002] Drive current is commonly used to control voltage, current, or power at a load. For example, a light-emitting diode (LED) driver can control the power supplied to one or more LEDs. LED drivers may include voltage regulators, line regulators, or DC-DC power converters (such as buck-boost, buck, boost, or another DC-DC power converter). DC-DC power converters can be particularly useful for LED drivers to regulate the current through an LED string.

[0003] Some LED circuits consist of a large number of individually controllable LEDs arranged in a two-dimensional matrix. These individually controllable “miniature” LEDs can be driven to provide different lighting for different driving conditions (e.g., high beam or low beam) or to provide advanced lighting effects.

[0004] An advanced vehicle headlight system is, for example, an application of such a matrix LED circuit, whereby lighting effects associated with vehicle operation can be used to improve the driving experience and enhance vehicle safety. Summary of the Invention

[0005] Generally, this disclosure relates to circuitry for controlling and driving pixelated light sources, such as those used in advanced vehicle headlight systems, for example, so-called miniature light-emitting diode (micro-LED) matrices. The circuitry of this disclosure can be configured to control a cluster of micro-LEDs using a shared operational transconductance amplifier (OTA) in a voltage regulation loop. To facilitate the sharing of OTAs for the micro-LED clusters, the circuitry of this disclosure can utilize an equalizer sub-circuit.

[0006] In some examples, this disclosure describes a lighting circuit configured to control an N×M cluster of miniature light-emitting diodes (micro-LEDs), where N and M are positive integers. The lighting circuit may include: an amplifier circuit configured to receive a reference voltage and output an regulated voltage; and an equalizer subcircuit. The lighting circuit may also include N×M power stages configured to drive N×M micro-LEDs, wherein the equalizer subcircuit is configured to output the regulated voltage to each of the N×M power stages.

[0007] In some examples, this disclosure describes a method including controlling an N×M cluster of microLEDs, where N and M are positive integers, the method comprising: receiving a reference voltage by an amplifier circuit; outputting an regulated voltage by the amplifier circuit to an equalizer sub-circuit; outputting the regulated voltage by the equalizer sub-circuit to each of N×M power stages; and driving the N×M microLEDs by the N×M power stages based on the regulated voltage.

[0008] In some examples, this disclosure describes a lighting system comprising: a matrix of miniature light-emitting diodes (micro-LEDs), wherein the matrix includes more than 2000 micro-LEDs; and a plurality of lighting circuits, each configured to control a unique N×M cluster of micro-LEDs, where N and M are positive integers. Each of the plurality of lighting circuits may include: an amplifier circuit configured to receive a reference voltage and output a regulated voltage; an equalizer subcircuit; and N×M power stages configured to drive the N×M micro-LEDs, wherein the equalizer subcircuit is configured to output the regulated voltage to each of the N×M power stages. The system may include a vehicle headlight module or another type of lighting module utilizing pixelated light sources.

[0009] Details of these and other examples are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the specification and drawings, as well as from the claims. Attached Figure Description

[0010] Figure 1 The diagram is a block diagram of a system including vehicle headlights and a processor, consistent with this disclosure.

[0011] Figure 2 This is a conceptual diagram showing a miniature LED driver matrix and a conceptual close-up view of a driver circuit connected to a miniature LED.

[0012] Figure 3A and Figure 3B This is a circuit diagram showing some example LED and driver arrangements.

[0013] Figure 4A and Figure 4B This is a block diagram illustrating an example LED driver that can provide output current (Iout) to a single LED.

[0014] Figure 5 This is a block diagram showing a circuit consistent with this disclosure.

[0015] Figure 6 This is another block diagram showing a circuit consistent with this disclosure.

[0016] Figure 7 This is a block diagram illustrating a system consistent with this disclosure.

[0017] Figure 8 Including timing diagrams and circuit diagrams consistent with this disclosure to illustrate the use of PWM components for controlling the state of LEDs using circuitry.

[0018] Figure 9 It is a circuit diagram showing the layout of the circuit components.

[0019] Figure 10 This is a flowchart illustrating a method consistent with this disclosure. Detailed Implementation

[0020] This disclosure relates to circuitry used to control and drive pixelated light sources, such as those used in advanced vehicle headlight systems, for example, matrices of so-called micro-light-emitting diodes (micro-LEDs). High-density micro-LED drivers with dense micro-LED pitch (e.g., less than 100 micrometers or less than 50 micrometers) face significant challenges, including the accuracy of regulating current for each micro-LED driver.

[0021] The circuit disclosed herein can be configured to control a cluster of microLEDs using a shared operational transconductance amplifier (OTA) in a voltage regulation loop. To facilitate the sharing of the OTA for the microLED cluster, the circuit disclosed herein can utilize an equalizer subcircuit controlled by a pulse modulation (PM) signal, such as a pulse width modulation (PWM) signal. Each power stage can be connected to the shared OTA only when the power stage controls the microLED to be ON.

[0022] The circuit area required to implement the equalizer subcircuit can be smaller than the circuit area required to implement an independent OTA for each microLED driver. The additional circuit area can be utilized to facilitate a larger (more accurate) OTA for the cluster than could be achieved if a separate OTA were implemented for each microLED in the cluster.

[0023] Circuits can be used to control and drive light-emitting elements of pixelated light sources, such as a large number (e.g., more than 2000) of miniature light-emitting diodes (micro-LEDs). Techniques and circuits can improve the accuracy of the so-called "kilis" (i.e., gain factor) that can be achieved for high-density driver circuits associated with high-density pixelated light sources. Micro-LEDs can generally be referenced to LEDs with a lateral pitch of less than 100 micrometers, and in some cases less than 50 micrometers. As the size of micro-LEDs and their corresponding driver circuits becomes increasingly smaller, challenges arise regarding circuit layout and performance. One particular challenge is the quality and performance of the over-the-air (OTA), which affects the accuracy of the regulation loop controlling the micro-LEDs. In the case of high-density systems, circuit area limitations can hinder the ability to achieve a sufficiently high-quality OTA for each micro-LED driver circuit, which may be required to achieve acceptable accuracy of the gain factor (also referred to here as "kilis").

[0024] Similarly, the circuitry of this disclosure shares an OTA on a voltage regulation loop used by several microLED drivers within a microLED cluster. To facilitate this sharing of the OTA for the microLED cluster, the circuitry of this disclosure can utilize an equalizer sub-circuit controlled by a PM signal, for example, the same PM signal used by the power stages of individual driver circuits for the microLEDs. In this manner, each power stage can be connected to the shared OTA only when the power stage controls the microLEDs to be in the ON state. The OTA is operationally "ON" whenever at least one of the microLEDs in the cluster is ON, and operationally "OFF" only when all the microLEDs in the cluster are OFF.

[0025] The circuit area required to implement the equalizer subcircuit can be smaller than the circuit area required to implement a separate OTA for each microLED driver. The additional circuit area can be utilized to facilitate a larger and more accurate OTA for the cluster (and associated logic or Kilis elements for the OTA) than could be achieved if separate OTAs and logic were implemented for each microLED in the cluster. This circuitry is particularly desirable when the dimensions (or pitch) of the microLEDs are less than 100 micrometers, and even more specifically, less than 50 micrometers.

[0026] Figure 1This is a block diagram illustrating a system consistent with this disclosure, including lighting circuitry 10 and processor 12. Processor 12 can provide control signals to lighting circuitry 10. Based on the control signals, LED driver circuitry 102 can provide individual control of LED 106. Control signals may include PM signals, such as PWM signals, pulse density modulation signals, or other types of modulation signals. LED driver circuitry 102 may include transistors controlled to operate as DC / DC converters to deliver regulated current to LED 106.

[0027] According to this disclosure, the lighting circuit 10 can be configured to control individual N×M microLED clusters in a manner that can improve the accuracy of the so-called kilis (gain factor) in the adjustment loop for the cluster. By sharing the OTA for the cluster and using an equalizer subcircuit to facilitate sharing, particularly desirable improvements can be achieved, such as making the surface area dimensions of the microLEDs and the corresponding microLED drivers very small, for example, having a pitch of less than 100 micrometers or less than 50 micrometers.

[0028] Figure 2 This is a conceptual diagram showing a miniature LED driver matrix 204 within an analog + digital core 202. Figure 2 Also included is a conceptual close-up view of a driver circuit 210 connected to a microLED 230. The microLED can be individually attached to a microLED driver, for example, as depicted with microLED 232, and arrows indicate the attachment of microLED 232 to the driver circuit 210 as a directly adjacent driver circuit. Driver circuit 210 (and other microLED driver circuits) includes a controllable transistor 212. A PM signal controls the ON-OFF state of transistor 212 to deliver a controllable amount of current through microLED 230. Power supply 220 can provide power via controllable transistor 212 to drive the current through microLED 230. The circuit of this disclosure can be implemented within an analog + digital core 202, such as... Figure 2 As shown.

[0029] A fundamental function of a high-density pixel matrix micro-LED driver is to absorb or provide regulated current from the cathode / anode of the micro-LED. Figure 3A and Figure 3B The illustration shows two different example layouts. Figure 3A The high-side configuration of the microLED 32 is shown, wherein a current source 302 is positioned between the microLED 32 and ground to deliver current through the microLED. Figure 3B This shows a low-side configuration of the micro LED 32, where the current source 304 is positioned at the power node (V). DDP Between ) and micro LED 34.

[0030] Each individual microLED in the matrix of microLEDs can physically generate a regulated output current (IOUTx) using a dedicated analog current signal (Iref), which can be determined by the formula: Where k is a constant “kilis” (gain factor), and IREF is a reference current. The IREF value is typically approximately equal across all microLED drivers, and the IREF value can be varied or adjusted within a defined range. This feature allows for adjustment of the matrix luminous flux as analog dimming. DCx may include a dedicated digital control signal for each microLED driver. This DCx signal may include duty cycle information provided by an embedded digital dimming PWM engine. The DCx signal can be used, for example, to modulate the individual pixel brightness defined in the intensity values ​​within a video frame by switching transistor 212 between on and off states. Figure 3A and Figure 3B These are two different example layouts of the regulation loop used to regulate IREF, which can be used to define the Vref for the LED clusters described herein. Similarly, in Figure 3A and 3B Two different examples of current source / sink regulation loop designs are shown in the figure.

[0031] Figure 4A and Figure 4B Showing with Figure 3A or Figure 3B An example of a consistent lighting circuit 40 for a single micro LED 44. Figure 4A In the example shown, circuit 402A is configured to control the power to LED 450A, which is connected to output pin 440A. Circuit 402A receives a reference current (I0) from current source 430A. REF Resistor 412A generates a reference voltage based on a reference current. OTA 410A receives the reference current and outputs a regulated voltage to power stage 420A (e.g., a power transistor). The source of power stage 420A is fed back to OTA for the regulation loop, and output resistor 414A is arranged to facilitate this regulation control loop. OTA 410A is essentially "on" whenever the transistor on power stage 420A is turned on.

[0032] exist Figure 4A The example shown has an LED 450A positioned on the low side, for example, connected to Vss_p, which can be grounded. Conversely, in Figure 4B The example shown has an LED 450B positioned on the high side, for example, connected to the power supply voltage (Vdd_p). Figure 4BIn the example shown, circuit 402B is configured to control the power to LED 450B connected to output pin 440B. Circuit 402B receives an IREF current from current source 430B, and resistor 412B generates a reference voltage based on the reference current. OTA 410B receives the reference current and outputs a regulated voltage to power stage 420B (e.g., a power transistor). The source of power stage 420B is fed back to OTA for the regulation loop, and output resistor 414B is arranged to facilitate this regulation control loop. OTA 410B is essentially "on" whenever the transistor on power stage 420B is turned on.

[0033] exist Figure 4A and Figure 4B In the example, OTA 410A and OTA 410B provide regulated voltages to drive the gates of source follower power stages 420A and 420B, thereby regulating the voltage node of the resistor-based Kilis structure. In this topology, the Kilis (gain factor) is defined as the ratio of the reference resistance to the power stage resistance (i.e., Kilis(k) = Rref / Rout). In high-density pixel matrices, a desirable product characteristic is the accuracy of the driver Kilis. The primary factor is the error in the Kilis introduced by the OTA. Generally, the larger the OTA, the better the accuracy, which can be attributed to temperature and process extension. Negligible errors in the Kilis are further introduced by the IREF current and resistors or other components defining the Kilis.

[0034] Use something similar to Figure 4A and Figure 4B The design of the miniature LED driver circuit shown can be based on the use of a single error amplifier and a dedicated IREF for each pixel driver. Using this method, a typical Kilis accuracy value is a single digital value in large pitch matrices (e.g., ≥50 μm), while a poorer double-digit value can be expected in finer pitch matrices (e.g., <50 μm). The main causes of error in Kilis accuracy can be related to area and technical scaling limitations.

[0035] In other words, in Figure 4A and Figure 4BThe circuits shown are desirable and effective for LED control, but they require an OTA (Over-The-Air) for each LED, which becomes difficult in terms of circuit area as the size of the LEDs and associated LED drivers become smaller. In particular, achieving acceptable accuracy for Kilis can be difficult as the OTA becomes smaller. Kilis accuracy with less than 10% error is desirable; for example, a target of 7% error or better is desired. However, due to size and scaling limitations, circuits with similar OTA values... Figure 4A or Figure 4B In the case of the circuit shown, a 14% error accuracy is the most probable level of accuracy when the pitch is equal to or less than 50 micrometers. This is attributed to technological scaling and size reduction, where there is insufficient space.

[0036] To address the challenges, this disclosure proposes a circuit solution utilizing an OTA (Over-The-Air) for a cluster of microLEDs, which can achieve Kiris accuracy with an error of less than 10% or less than 7%. The cluster may include 4, 6, 8, 10, 16, or typically any number of microLEDs. To facilitate the sharing of the OTA for the microLED cluster, the circuit of this disclosure can utilize an equalizer subcircuit controlled by a PM (Power Transistor) signal, such as a PWM (Pulse Width Modulation) signal. In some examples, the same PM signal used to control the power transistors in the power stages can be used by a switch in the equalizer subcircuit. Whenever the power stage controls the microLEDs to be on, the corresponding switch in the equalizer circuit can connect the power stage to the OTA. Some or all of the circuitry in the microLED driver circuitry (e.g., the power stages) can be simultaneously connected to the OTA. The OTA remains "on" as long as one power meter in the power stage controls the microLEDs to be on, and the OTA is operably "off" only when all power stages for the cluster and all microLEDs controlling the cluster are "off".

[0037] Figure 5 This is a circuit consistent with this disclosure. In some examples, amplifier 504, equalizer sub-circuit 506, and power stages 510, 512, 514, and 516 define an illumination circuit configured to control N×M miniature LED clusters 520, 522, 524, and 526. N and M are positive integers, and N×M is 2 or greater, meaning that N×M is a plurality. Therefore, in Figure 5 In the example shown, four miniature LEDs 520, 522, 524, and 526 are illustrated, where M and N can each be 2, or M can be 4 and N can be 1, or M can be 1 and N can be 4. Other cluster sizes may also be used in accordance with this disclosure.

[0038] exist Figure 5 In the circuit, Vref generator 502 receives the reference current (Iref). REF And a voltage reference (V) is generated based on the reference current. REF Amplifier circuit 504 is configured to receive a reference voltage and output an regulated voltage (V). REG For example, amplifier circuit 504 may include an OTA (over-amplifier) ​​or another suitable amplifier structure useful for a voltage regulation loop. N×M power stages (four power stages in this example) 510, 512, 514, 516 are configured to drive N×M miniature LEDs 520, 522, 524, 526. Equalizer sub-circuit is configured to output a regulated voltage to each of the N×M power stages, for example, to the gate of a power transistor in each of the N×M power stages, each power stage may include a source follower power transistor. In other words, each of the N×M power stages 510, 512, 514, 516 may include a source follower power stage, wherein the gate control voltage for the cluster is defined by amplifier 504, and the connection to the gate control voltage of each of the N×M power stages 510, 512, 514, 516 is defined by equalizer sub-circuit 506.

[0039] N×M micro-LED clusters 520, 522, 524, and 526 can be a small part of a matrix of micro-LEDs, which can be associated with vehicle headlights or another lighting system. Therefore, in Figure 5 The circuitry shown can be replicated for clusters of N×M power levels to control an entire microLED matrix. This entire matrix could, for example, comprise approximately 2000 microLEDs, approximately 4000 microLEDs, approximately 10000 microLEDs, approximately 10000 microLEDs, approximately 90000 microLEDs, approximately 100000 microLEDs, or a matrix of any size. Similarly, vehicle headlights are one use case, but the lighting circuitry can be used in other matrix lighting applications.

[0040] Each of the N×M power stages 510, 512, 514, 516 can be arranged on a circuit region with a dimension of less than 100 micrometers (e.g., the pitch between power stages). In some cases, each of the N×M power stages 510, 512, 514, 516 can be arranged on a circuit region with a pitch of less than 50 micrometers. With these very small dimensions, implementing an accurate amplifier for each power stage becomes difficult. To address this problem, the circuit of this disclosure implements an amplifier 504 for the entire LED power stage cluster, and uses an equalizer sub-circuit 506, which may include a set of high-ohm switches to provide access to the output of amplifier 504.

[0041] In some examples, the equalizer subcircuit 506 may include multiple switches arranged and controlled to output regulated voltages to each of the N×M power stages 510, 512, 514, 516 to regulate the source and gate of each of the N×M power stages 510, 512, 514, 516. The N×M power stages 510, 512, 514, 516 may include power transistors controlled via PM signals to deliver current to the N×M microLEDs. Different PM signals for different transistors of the N×M power stages 510, 512, 514, 516 may also be used to control the multiple switches of the equalizer subcircuit 506. In some cases, different PM signals for different transistors of the N×M power stages 510, 512, 514, 516 may be used for digital dimming on a pixel-by-pixel basis.

[0042] The control switch of the equalizer subcircuit 506 can be a logic signal based on several PWM components. The PWM signal can be defined by a component with a large PWM duty cycle, wherein the PWM component defines the on-off state for each of the N×M miniature LEDs within the PWM duty cycle.

[0043] The equalizer subcircuit 506 may include another switch to facilitate feedback in the voltage regulation loop for the N×M microLED clusters 520, 522, 524, 526. Therefore, the output of each of the N×M power stages is also connected back to the equalizer circuit. Thus, the multiple switches of the equalizer subcircuit 506 may also include feedback switches, wherein the equalizer subcircuit 506 is configured to deliver a feedback signal (FB) to the amplifier 504. In this case, the feedback signal is defined by controlling the feedback switches of the equalizer subcircuit 506, for example, based on a logic signal. In this or possibly other ways, the output of each of the N×M power stages 510, 512, 514, 516 is connected to the equalizer subcircuit 506, and the equalizer circuit is configured to deliver feedback information (FB) to the amplifier 504 to form a voltage regulation loop for the N×M microLED clusters.

[0044] An equalizer subcircuit can be introduced for each N×M cluster of microLEDs in a high-density pixel matrix, with the aim of sharing a single over-the-air (OTA) across the power stages of each N×M cluster, thereby improving LED illumination (e.g., accuracy, dropout, power consumption, or other factors) for each microLED cluster acting as a driver. In fact, using a single OTA instead of M×N OTAs can result in circuit area savings, which can be used to improve the performance of M×N shared regulation loops. The area of ​​the equalizer subcircuit 506 can be considered negligible in some cases because it can be implemented using a few small-sized metal-oxide-semiconductor transistors. In some examples, the area required to implement the equalizer subcircuit 506 can be significantly less than the area required to implement three additional amplifiers. Therefore, by facilitating sharing through a single amplifier 504 and implementing the equalizer subcircuit 506, circuit area savings can be achieved, allowing for a larger or more accurate amplifier 504 that can be implemented in other ways.

[0045] The same PWM signal used to control the on / off states of the power transistors in power stages 510, 512, 514, and 516 can also be used to control the switching of the equalizer subcircuit 506, so that the regulated output of amplifier 504 is only connected to those power stages that control the LEDs to be on. This type of coordinated control can also achieve power efficiency.

[0046] In pixelated lighting devices, the activation of the current sink / source of a micro-LED within a PWM cycle can be divided into smaller components within the PWM cycle. The PWM cycle can define the duty cycle, which can be divided into 2^10 = 1024 PWM components corresponding to the minimum duty cycle resolution. Depending on the selected duty cycle, all current sinks / sources are active for a certain number of PWM components. Control of the same PWM components in the power stage can also be used to control the switching of the equalizer subcircuit 506 for both output control and feedback control.

[0047] Figure 6 This is another block diagram showing a circuit consistent with this disclosure. Figure 6 and Figure 5 Consistent, but Figure 6 Showing the ratio Figure 5More detailed examples. In some examples, error amplifier 608, equalizer sub-circuit 620, and power stages 640, 650, 660, and 660 are configured to control an illumination circuit of an N x M cluster of microLEDs represented by microLEDs 692, 694, and 696. Output pins 682, 684, and 686 of the illumination circuit can facilitate connections from the illumination circuit to the microLEDs 692, 694, and 696. Again, N and M are positive integers, and N x M is 2 or greater, meaning N x M is a plurality. In other words, at least one of N or M can be a positive integer greater than 1. Figure 6 In this context, miniature LEDs 692, 694, and 696 typically represent any number of LEDs. For most practical applications, N×M can be less than 100 or less than 50, although the circuit can also be used for larger clusters.

[0048] exist Figure 6 In the circuit, Vref generator 602 can receive a reference current and generate a voltage reference (V) based on the reference current. REF Vref generator 602 may include a reference resistor 604 or another defined element to limit Vref based on the Iref current. Error amplifier circuit 608 (e.g., OTA) is configured to receive a reference voltage (V... REF And output regulated voltage (V) OTA Therefore, the error amplifier circuit 608 can introduce a gain that can also be defined or influenced by the transconductance (gm) 610 of the error amplifier circuit 608, and the error amplifier circuit 608 can transfer the current I through the resistor 612. OTA Output to generate regulated output voltage V OTA The feedback (Vfb) for the entire cluster is received by error amplifier 608 at node 614 to form the signal for V. OTA The closed-loop voltage regulation.

[0049] N×M power stages (typically represented by power stages 640, 650, and 660) are configured to drive N×M microLEDs (represented by microLEDs 692, 694, and 696). The equalizer subcircuit 620 may include an analog OTA equalizer comprising a high-ohm switch (high-Z switch). Specifically, in this example, the equalizer subcircuit 620 includes a first set of output switches 622 and a second set of feedback switches 632. The output switches 622 and feedback switches 632 may be controlled by the same PWM signal (e.g., the same PWM component) used to control the transistors in power stages 640, 650, and 660. In this way, at any given time, the power stages drive the microLEDs in an "on" state, and the output switches 622 are controlled synchronously by the same PM signal to ensure V OTAIt can be used in power stages. Similarly, whenever the power stage drives the micro-LED to the "on" state, the feedback switch 632 is controlled synchronously by the same PM signal to ensure V FB Influenced by power stage feedback.

[0050] The equalizer sub-circuit 620 can be configured to adjust the voltage (V) OTA The output is fed to each of the N×M power stages, for example, to the gate of each of the N×M power stages 640, 650, and 660. Power stages 640, 650, and 660 may include source follower power transistors. The output of each of the power stages 640, 650, and 660 is fed back to the input of each of the power stages 640, 650, and 660 via a set 670 of output resistors 672, 674, and 676 to form a separate open-circuit regulation loop for providing current to each of the microLEDs 692, 694, and 696. Each of the N×M power stages 640, 650, and 660 may include a source follower power transistor, wherein the gate control voltage for the cluster is defined by an error amplifier 608, and the connection to the gate control voltage of each of the N×M power stages 640, 650, and 660 may be defined by an equalizer subcircuit 620. Each of the power stages 640, 650, and 660 may define a gain, which may also be defined or influenced by the transconductance (gm) 642, 652, and 662 of each of the power stages 640, 650, and 660, which may be different or similar for some or all of the LEDs 692, 694, and 696.

[0051] Individual feedback from the inputs of each of the power stages 640, 650, and 660 via output resistors 672, 674, and 676 defines individual regulation loops (i.e., open loops) at nodes 644, 654, and 664. Furthermore, feedback from the combination of output resistors 672, 674, and 676 is also fed back via feedback switch 632 to define a second regulation loop (i.e., closed loop) for error amplifier 608, thereby regulating V for the entire micro-LED cluster. OTA .

[0052] exist Figure 6 In the example shown, output switch 622 includes individual switches 624, 626, and 628 corresponding to each of power stages 640, 650, and 660. Similarly, feedback switch 632 includes individual switches 634, 636, and 638 corresponding to each of power stages 640, 650, and 660. However, other more complex switching circuitry can also be used by equalizer sub-circuit 620 consistent with this disclosure.

[0053] Individual switches 624, 626, 628, 634, 636, and 638 within the equalizer subcircuit 620 may include high-ohm switches (e.g., in the range of several hundred Kohms). One purpose of switches 624, 626, 628, 634, 636, and 638 is to connect / disconnect the output and feedback from the shared error amplifier 608 to “N×M” power stages at the beginning of each PWM component. The equalizer switches can be driven by a digital PWM signal; when the PWM signal is set high (meaning the pixel is on), the corresponding output switch 622 and feedback switch 632 are immediately activated and remain on for all corresponding valid PWM components.

[0054] In some examples, the same logic control circuitry defining the switching signals for the micro-LED drivers (e.g., in power stages 640, 650, 660) can be used as the logic controlling the switches within the equalizer subcircuit 620. In other words, the same control logic can be used, but control signals can be delivered simultaneously to the micro-LED driver switches in power stages 640, 650, 660, as well as the output switches 622 and feedback switches 632 of the equalizer subcircuit 506. The error amplifier 608 is only off when all LEDs 692, 694, 696 are off for a given component. One or all output stages can be connected to the OTA at any time to obtain the appropriate gate voltage. Sharing the gate and feedback produces the same output current (for a given component), but the PM signal can still be modulated with a pixel-by-pixel duty cycle.

[0055] Generally, the equalizer subcircuit 620 includes multiple switches (e.g., output switches 622) arranged and controlled to output regulated voltages to each of the N×M power stages 640, 650, 660 to regulate the source and gate of the power transistors within each of the N×M power stages 640, 650, 660. The N×M power stages 640, 650, 660 may include power transistors controlled via pulse-modulated signals to deliver current to N×M miniature LEDs 692, 694, 696. In some cases, different pulse-modulated signals for different power transistors are also used to control the multiple switches (e.g., output switches 622) of the equalizer subcircuit. The output switches 622 controlling the equalizer subcircuit 620 may be based on logic signals defining several PWM components, where each PWM component defines an on-off state for each of the N×M miniature LEDs within a PWM duty cycle. Furthermore, the output of each of the N×M power stages 640, 650, and 660 is connected back to the equalizer circuit, wherein the multiple switches of the equalizer circuit also include a feedback switch 632, wherein the equalizer circuit is configured to convert the feedback signal (V) fbThe feedback signal is delivered to the error amplifier 608, whereby the feedback signal is also defined by controlling the feedback switch 632 based on logic signals (e.g., the same logic signals that control the power transistors of power stages 640, 650, 660 and the same logic signals that control the output switch 622).

[0056] Figure 7 This is a block diagram illustrating a system consistent with this disclosure. Figure 7 The system shown is essentially in Figure 6 A combination of two or more circuits as shown. Although in Figure 6 The circuit described in Figure 7 The system diagram is copied twice, any number of times with Figure 6 Similar circuits can be like Figure 7 The LEDs shown are combined to control any number of LEDs in a very large matrix. In other words, it's similar to... Figure 6 The circuit shown can be as follows Figure 7 The diagram shows combinations used to control any number of subsets of microLEDs. Each subset of microLEDs can be controlled via a method such as... Figure 6 The circuits shown are controlled using a shared OTA (Over-The-Air). Each circuit can be connected to a common input bus 718, such as... Figure 7 As shown. Figure 7 Spanning two pages in the accompanying drawings, nodes A, B, and C are connected to each other; that is, at node A, 748A is connected to 748B. At node B, 758A is connected to 758B, and at node C, 768A is connected to 768B to define the frame surrounding the system.

[0057] Figure 7 Details and Figure 6 The details are the same, although the circuit is copied twice. Similarly, any number of similar... Figure 6 The circuit can be like Figure 7 The following components are combined as shown. Vref generators 702A and 702B operate similarly to Vref generator 602 described above. Error amplifiers 708A and 708B operate similarly to error amplifier 608. Equalizer subcircuits 720A and 720B operate similarly to equalizer subcircuit 620. Output switches 722A and 722B operate similarly to output switch 622, and feedback switches 732A and 732B operate similarly to feedback switch 632. Power stages 740A, 750A, and 760A, and power stages 740B, 750B, and 760B operate similarly to power stages 640, 650, and 660. Output resistor sets 770A and 770B operate similarly to output resistor set 670.

[0058] Similar to Figure 7The system shown can include any number of [interconnections / components]. Figure 6 A circuit similar to the one used to control any number of miniature LEDs 792A, 794A, 796A, 792B, 794B, 796B. In other words, in Figure 7 The system shown can typically represent a system used to control the entire micro-LED matrix. Numerous similar systems exist. Figure 6 Individual circuits can be used together (e.g., ... Figure 7 (As shown) generates a system for controlling the entire micro-LED matrix, which may include approximately 2,000 micro-LEDs, approximately 4,000 micro-LEDs, approximately 10,000 micro-LEDs, approximately 16,000 micro-LEDs, approximately 100,000 micro-LEDs, or any number of micro-LEDs within a large matrix.

[0059] Figure 8 An example of a PWM pattern focused on the first PWM component 802 is shown. In this example, in the first component, LED_0 is on for the first component (as shown at 806), LED_1 is off (i.e., there is no "on" signal for LED_1), and LED_n is on at 804 for the first three components. LED_1 is also shown as "on" in the 1021st component at 808. In this example, there are 1024 components (i.e., from 0 to 2023). The duty cycle can define other numbers of components, and Figure 7 Only one example is shown.

[0060] Figure 8 The diagram also shows the corresponding circuit and control. Figure 8 The circuit shown is the first PWM quantum 802 consistent circuit. Figure 8 The circuit shown illustrates miniature LEDs 862, 864, and 866 connected to output pins 852, 854, and 856, and an regulated 1 mA current (or other value) can be selectively delivered to a single miniature LED 862, 864, or 866.

[0061] exist Figure 8 Two power supply nodes are labeled Vdd_p (which can correspond to 5 volts or another power supply volt value) and ground (which can correspond to actual ground or another reference voltage). Current source 860 delivers reference current to the circuitry and resistor 820 that define the reference voltage for OTA850. Miniature LEDs 862, 864, and 866 are controlled to be on or off by, for example, controlling power transistors 836, 840, and 844 according to PWM component control signals. Power transistors 836, 840, and 844 can be considered as output stages for controlling miniature LEDs 862, 864, and 866.

[0062] Output resistors 822, 824, and 826 can define a gain factor, which also depends on reference resistor 820. This gain can be the same or different, depending on whether a similar current is needed to drive each of the micro-LEDs 862, 864, and 866. Switches 828, 842, 830, 838, 832, and 834 can represent switches within the equalizer subcircuit, controlled by the same PWM component used to control power transistors 836, 840, and 844 to define the on-off state of the micro-LEDs 862, 864, and 866. Therefore, when power transistor 836 is on, such as during the first component 802, switches 832 and 834 (of the equalizer subcircuit) are controlled to be on. Similarly, when power transistor 838 is off, such as during the first component 802, switches 830 and 838 (of the equalizer subcircuit) are controlled to be off. And when power transistor 844 is on, such as during the first component 802, switches 828 and 842 are controlled to be on. In this way, OTA 850 can be shared to define the regulated output voltage for the entire microLED cluster, while individual microLED control can be defined by PWM component control. OTA 850 is essentially switched in only when the corresponding microLED is driven on to provide the regulated V. OTA And it is switched out only when the corresponding microLED is disconnected in any given duty cycle component (and cannot be used with microLED drivers).

[0063] Figure 9 This is a conceptual diagram showing the circuit layout with the "key" identifying the OTA, design-for-test (DFT) circuitry, power stages, Kilis components, and logic. In the 2×2 cluster shown on the left, the circuit layout includes separate OTAs for each microLED pixel and microLED driver. As shown, when the track pitch is less than 50 micrometers, there is no extra space to produce larger and better OTAs (and associated Kilis and logic components). The 2×2 cluster on the right shows a 25% surface area saving in the elimination of three OTAs compared to the 2×2 cluster on the left. In the 2×2 cluster shown on the right, one OTA is used to serve all four microLED drivers. This 25% saving is sufficient to allow for the area of ​​the equalizer sub-circuit and also increases the size of the individual OTA in the 2×2 cluster shown on the right.

[0064] Figure 10 This is a flowchart illustrating a method consistent with this disclosure. Figure 10 From Figure 6 The circuit shown is a description from a theoretical perspective, although other circuits can perform the same method. (As...) Figure 10As shown, the amplifier circuit (e.g., error amplifier 608) receives a reference voltage (Vref) (1002). The amplifier circuit (e.g., error amplifier 608) outputs a regulated voltage (V... OTA (1004). Equalizer sub-circuit 620 receives regulated voltage (V) OTA (1006), and will adjust the voltage (V) OTA The output is fed into N×M power stages 640, 650, 660 (1008). These N×M power stages 640, 650, 660 then adjust the voltage (V... OTA Drive N×M miniature LEDs 692, 694, 696 (1010). Adjust the voltage (V) OTA It can limit the regulation voltage of both the gate and source of the power transistors in each of the N×M power levels 640, 650, 660, and the PWM signal can control the on-off state on a pixel-by-pixel basis.

[0065] The techniques described in this disclosure can be implemented in circuit arrangements. In various examples, the techniques can be implemented at least in part in circuit arrangements, hardware, software, firmware, or any combination thereof. For example, various aspects of the described techniques can be implemented within one or more logic elements, processors including one or more microcontrollers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuit arrangements, and any combination of such components. The terms "processor" or "processing circuit arrangement" can generally refer to any one of the logic circuit arrangements described above, alone or in combination with other logic circuit arrangements or any other equivalent circuit arrangements. A control unit, including hardware, can also perform one or more of the techniques of this disclosure.

[0066] Such circuit arrangements, hardware, software, and firmware can be implemented within the same device or integrated circuit or in separate devices to support the various operations and functions described in this disclosure. Furthermore, any of the described units, modules, or components can be implemented together or separately as discrete but interoperable logic devices. The depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Rather, the functions associated with one or more modules or units can be performed by separate hardware or software components, or integrated in common or separate hardware or software components.

[0067] One or more aspects of this disclosure can also be implemented in software, for example, particularly for logic or decisions performed based on circuit outputs, in which case those aspects of the technology described in this disclosure can also be embodied or encoded in a computer-readable medium including instructions, such as a computer-readable storage medium. Instructions embedded or encoded in a computer-readable storage medium can cause a processor to perform a method, for example, when the instructions are executed. In this example, the instructions can be stored in memory, which may include random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other computer-readable media.

[0068] The following terms may illustrate one or more aspects of this disclosure.

[0069] Clause 1: A lighting circuit configured to control an N×M cluster of miniature LEDs, where N and M are positive integers, the lighting circuit comprising: an amplifier circuit configured to receive a reference voltage and output an regulated voltage; an equalizer sub-circuit; and N×M power stages configured to drive the N×M miniature LEDs, wherein the equalizer sub-circuit is configured to output the regulated voltage to each of the N×M power stages.

[0070] Clause 2: The lighting circuit according to Clause 1, wherein the lighting circuit is configured to control an N-M cluster within a matrix of miniature LEDs associated with the vehicle headlights.

[0071] Clause 3: The lighting circuit according to Clause 1 or 2, wherein each of the N×M power stages is arranged on a circuit area having a pitch of less than 100 micrometers.

[0072] Clause 4: A lighting circuit according to any one of Clauses 1-3, wherein each of the N×M power stages includes a source follower power stage.

[0073] Clause 5: A lighting circuit according to any one of Clauses 1-4, wherein N=2 and M=2.

[0074] Clause 6: A lighting circuit according to any one of Clauses 1-5, wherein the equalizer subcircuit comprises a plurality of switches arranged and controlled to output a regulated voltage to each of the N×M power levels to regulate the source and gate of each of the N×M power levels.

[0075] Clause 7: The lighting circuit according to Clause 6, wherein the N×M power stages include power transistors controlled by pulse modulation signals to deliver current to N×M miniature LEDs, wherein different pulse modulation signals for different power transistors in the power transistors are defined by controlling multiple switches of the equalizer subcircuit.

[0076] Clause 8: The lighting circuit according to Clause 6 or 7, wherein the multiple switches of the control equalizer subcircuit are based on a logic signal that defines a number of PWM components, wherein the PWM components define an on-off state for each of the N×M microLEDs within the PWM duty cycle.

[0077] Clause 9: A lighting circuit according to any one of Clauses 6-8, wherein the output of each of N×M power stages is connected to an equalizer subcircuit, wherein the multiple switches of the equalizer subcircuit further include a feedback switch, wherein the equalizer subcircuit is configured to deliver a feedback signal to an amplifier, wherein the feedback signal is defined by controlling the feedback switch based on a logic signal.

[0078] Clause 10: A lighting circuit according to any one of Clauses 1-9, wherein the output of each of the N×M power stages is connected to an equalizer subcircuit, wherein the equalizer subcircuit is configured to deliver a feedback signal to an amplifier.

[0079] Clause 11: A method for controlling an N×M cluster of microLEDs, wherein N and M are positive integers, the method comprising: receiving a reference voltage by an amplifier circuit; outputting an regulated voltage by the amplifier circuit to an equalizer sub-circuit; outputting the regulated voltage by the equalizer sub-circuit to each of N×M power stages; and driving the N×M microLEDs by the N×M power stages based on the regulated voltage.

[0080] Clause 12: The method described in Clause 11, wherein each of the N×M power stages includes a source follower power stage.

[0081] Clause 13: The method described in accordance with Clause 11 or 12, wherein N=2 and M=2.

[0082] Clause 14: The method according to any one of Clauses 11-13, wherein the equalizer subcircuit includes a plurality of switches, the method further comprising: controlling the plurality of switches to output an regulated voltage to each of N×M power stages.

[0083] Clause 15: The method according to Clause 14, wherein the N×M power stages include power transistors controlled via pulse modulation signals to deliver current to the N×M micro LEDs, the method further comprising: controlling a plurality of switches of an equalizer subcircuit based on the pulse modulation signals.

[0084] Clause 16: The method described in Clause 14 or 15, wherein the multiple switches of the equalizer subcircuit are based on a logic signal that defines a number of PWM components, wherein the PWM components define an on-off state for each of the N×M microLEDs within the PWM duty cycle.

[0085] Clause 17: The method according to any one of Clauses 14-16 further comprises: delivering the output of each of the N×M power stages back to the equalizer subcircuit, wherein a plurality of switches of the equalizer subcircuit further include feedback switches; and delivering a feedback signal from the equalizer subcircuit to the amplifier, wherein the feedback signal is defined by controlling the feedback switches based on logic signals.

[0086] Clause 18: The method according to any one of Clauses 11-17, wherein the output of each of the N×M power stages is connected to an equalizer subcircuit, wherein the equalizer subcircuit is configured to deliver a feedback signal to an amplifier.

[0087] Clause 19: A lighting system comprising: a micro-LED matrix, wherein the matrix includes more than 2000 micro-LEDs; a plurality of lighting circuits, each lighting circuit being configured to control a unique N×M cluster of micro-LEDs, wherein N and M are positive integers, wherein each of the plurality of lighting circuits includes: an amplifier circuit configured to receive a reference voltage and output an regulated voltage; an equalizer sub-circuit; and N×M power stages configured to drive the micro-LEDs, wherein the equalizer sub-circuit is configured to output the regulated voltage to each of the N×M power stages.

[0088] Clause 20: The lighting system as described in Clause 19, wherein the lighting system includes vehicle headlights.

[0089] Clause 21: The lighting system according to Clause 19, wherein each of the plurality of lighting circuits comprises the lighting circuit of any one of Clauses 1-10.

[0090] Various aspects have been described in this disclosure. These and other aspects are within the scope of the following claims.

Claims

1. An illumination circuit configured to control N x M clusters of micro light emitting diodes (LEDs), where N and M are positive integers, the illumination circuit comprising: an amplifier circuit configured to receive a reference voltage and output a regulated voltage; an equalizer sub-circuit; and N x M power stages configured to drive N x M micro LEDs, where the equalizer sub-circuit is configured to output the regulated voltage to each of the N x M power stages.

2. The illumination circuit of claim 1, wherein the illumination circuit is configured to control the N by M clusters within a matrix of the micro LEDs associated with a vehicle headlamp.

3. The illumination circuit of claim 1, wherein each of the N x M power stages is disposed on a circuit area having a pitch less than 100 microns.

4. The illumination circuit of claim 1, wherein each of the N x M power stages comprises a source follower power stage.

5. The illumination circuit of claim 1, wherein N = 2; and M=2。 6. The illumination circuit of claim 1, wherein the equalizer sub-circuit comprises a plurality of switches arranged and controlled to output the regulated voltage to each of the N x M power stages to regulate a source and a gate of each of the N x M power stages.

7. The illumination circuit of claim 6, wherein the N x M power stages comprise power transistors controlled via pulse modulation signals to deliver current to the N x M micro LEDs, wherein by controlling the plurality of switches of the equalizer sub-circuit, different pulse modulation signals for different ones of the power transistors are defined.

8. The illumination circuit of claim 7, wherein controlling the plurality of switches of the equalizer sub-circuit is based on a logic signal defining a number of pulse width modulation (PWM) components, wherein the PWM components define on-off states within a PWM duty cycle for each of the N x M micro LEDs.

9. The illumination circuit of claim 8, wherein an output of each of the N x M power stages is connected to the equalizer sub-circuit, wherein the plurality of switches of the equalizer sub-circuit further comprise a feedback switch, wherein the equalizer sub-circuit is configured to deliver a feedback signal to the amplifier, wherein by controlling the feedback switch based on the logic signal, the feedback signal is defined.

10. The illumination circuit of claim 1, wherein an output of each of the N x M power stages is connected to the equalizer sub-circuit, wherein the equalizer sub-circuit is configured to deliver the feedback signal to the amplifier.

11. A method of controlling N x M micro light emitting diodes (LEDs), where N and M are positive integers, the method comprising: receiving, by an amplifier circuit, a reference voltage; outputting, by the amplifier circuit, a regulated voltage to an equalizer sub-circuit; outputting, by the equalizer sub-circuit, the regulated voltage to each of N x M power stages; and ​ N x M micro-LEDs based on the regulated voltage.

12. The method of claim 11, wherein each of the N x M power stages comprises a source follower power stage.

13. The method of claim 11, wherein N = 2; and M=2。 14. The method of claim 11, wherein the equalizer sub-circuit comprises a plurality of switches, the method further comprising: controlling the plurality of switches to output the regulated voltage to each of the N x M power stages.

15. The method of claim 14, wherein the N x M number of power stages comprise power transistors that are controlled via a pulse modulation signal to deliver current to the N x M number of micro-LEDs, the method further comprising: controlling the plurality of switches of the equalizer sub-circuit based on the pulse modulation signal.

16. The method of claim 15, wherein controlling the plurality of switches of the equalizer sub-circuit is based on a logic signal defining a number of pulse width modulation (PWM) components, wherein the pulse width modulation components define on-off states within a PWM duty cycle for each of the N x M micro-LEDs.

17. The method of claim 16, further comprising: delivering an output of each of the N x M power stages back to the equalizer sub-circuit, wherein the plurality of switches of the equalizer sub-circuit further comprises a feedback switch; and delivering a feedback signal from the equalizer sub-circuit to the amplifier, wherein the feedback signal is defined by controlling the feedback switch based on the logic signal.

18. The method of claim 11, wherein an output of each of the N x M power stages is connected to the equalizer sub-circuit, wherein the equalizer sub-circuit is configured to deliver the feedback signal to the amplifier.

19. A lighting system comprising: a matrix of micro light emitting diodes (LEDs), wherein the matrix comprises greater than 2000 micro-LEDs; a plurality of lighting circuits, each lighting circuit configured to control a unique cluster of N x M micro-LEDs, wherein N and M are positive integers, wherein each of the plurality of lighting circuits comprises: an amplifier circuit configured to receive a reference voltage and output a regulated voltage; an equalizer sub-circuit; and N x M power stages configured to drive N x M micro-LEDs, wherein the equalizer sub-circuit is configured to output the regulated voltage to each of the N x M power stages.

20. The lighting system of claim 19, wherein the lighting system comprises a vehicle headlamp.

Images