Micro-led power considering abnormal pixel dynamic resistance

Abstract

Systems, apparatuses, methods, and computer-readable media for reducing the number of un-driven or under-driven uLEDs of a uLED die are discussed herein. One method can include identifying, by a controller of a micro light emitting diode (uLED) die, a dynamic series resistance (R d ) or forward voltage (V f ) of a uLED of the uLED die, selecting, by the controller and based on the identified R d or V f , a current level (I PWM_0 ) that is less than a maximum current level (I PWM_MAX ) provided by a uLED driver coupled to the uLED die, and causing, by the controller, current to be provided to the uLED driver at the selected current level.

Description

[0001] Priority requirements

[0002] This application claims the benefit of priority to U.S. Patent Application Serial No. 17 / 123021, filed December 15, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a light-emitting device and a control system for the light-emitting device, which is configured to reduce or eliminate dark aberrations caused by the abnormally high dynamic series resistance of a light-emitting diode (LED). Background Technology

[0004] In some applications, such as residential or commercial lighting, the user experience regarding the visual effect of the lighting is crucial. Automotive lighting is another application where user experience is paramount. If the dynamic series resistance of a light-emitting diode (LED) is high, the LED's forward voltage may exceed the supply voltage, and the LED may not operate as expected. Such LEDs can appear as black spots or darker areas among lit LEDs. Attached Figure Description

[0005] The accompanying drawings illustrate various views of an apparatus, system, or method according to some embodiments, including a control system capable of altering the light emitted from one or more light-emitting diodes (LEDs). The terms "front," "rear," "top," "side," and other directional terms are used merely for convenience in describing the apparatus and system, as well as other elements, and should not be construed as limiting in any way.

[0006] Figure 1 A logic block diagram of an embodiment of a system for driving a die comprising a matrix of micro light-emitting diodes (uLEDs) is shown by way of example.

[0007] Figure 2 A perspective view of an embodiment including an undriven and / or underdriven uLED die is shown by way of example.

[0008] Figure 3 A schematic diagram of an embodiment is shown by way of example, illustrating a graph of the efficiency of the driver circuit versus the relative dynamic series resistance of the abnormal uLED.

[0009] Figure 4 A conceptual block diagram of an embodiment of a package including a uLED matrix and corresponding driver circuitry is shown by way of example.

[0010] Figure 5 A circuit diagram of an embodiment of a uLED pixel (uLED driver circuit and corresponding uLED) is shown by way of example.

[0011] Figure 6 The example illustrates the consideration of dynamic series resistance (R) of anomalous pixels. d The logic circuit diagram of an embodiment of a system that drives a uLED matrix is ​​shown.

[0012] Figure 7 The R of multiple uLED matrix chips is illustrated through examples. d A diagram of an example of the distribution.

[0013] Figure 8 A circuit diagram of an embodiment of a uLED pixel is shown by way of example.

[0014] Figure 9 The R method used for analyzing uLEDs in uLED chips is illustrated through an example. d A schematic diagram of an embodiment of the system.

[0015] Figure 10 The example illustrates an anomaly R. d uLED and having lower R d A graph showing the current versus voltage of a uLED.

[0016] Figure 11 A graph showing the peak driver current (%) versus the dynamic series resistance of the uLED is presented as an example.

[0017] Figure 12 V is illustrated through examples. LED With abnormal R d A graph showing the relative dynamic resistance of the uLED.

[0018] Figure 13 A schematic diagram illustrating an embodiment of a method for driving uLED matrix chips is shown by way of example.

[0019] Figure 14 More detailed support is shown for, for example, relative to Figures 6-13 Examples of chip-level implementations of the functions discussed in the system.

[0020] Figure 15 A logic block diagram of a system including circuitry that can be contained in a uLED package is shown by way of example.

[0021] Figure 16 A block diagram of an embodiment of a machine (e.g., a computer system) for implementing one or more embodiments is shown by way of example. Detailed Implementation

[0022] Compact, pixelated LEDs, such as those in micro-LED (sometimes called "uLED") arrays on a uLED die, can comprise a large monolithic die area. uLED arrays can be used in automotive lighting, such as headlights, taillights, parking lights, fog lights, turn signals, etc. Such applications are merely examples, and many other applications of uLED arrays are possible.

[0023] uLED arrays may include uLED dies integrated with driver electronics for controlling the brightness of individual pixels. The driver electronics can be fabricated using, for example, complementary metal-oxide-semiconductor (CMOS) materials or processes, or other semiconductor manufacturing processes.

[0024] In some embodiments, the driver electronics (uLED drivers) can implement a linear driving scheme. Linear driving is a practical solution for this type of control electronics, especially for large uLED array configurations. However, special care needs to be taken in controlling the voltage supplied to the driver electronics in linear driving schemes to provide both a stable uLED current supply and acceptable heat loss. To help ensure that more uLED drivers operate above their compliance voltage (at which they provide sufficient electrical power to the corresponding uLED driven by the driver), the voltage supplied to the driver electronics is typically set higher than the highest forward voltage (V0) of the uLEDs in the array. f However, such a setup is not effective for temperature or energy.

[0025] The advantage of monolithic uLED chips is that they facilitate the forward voltage (V) within the uLED population. f Narrow deviation (e.g., standard deviation < 100 mV). This positive voltage (V f The uniformity of the voltage distribution reduces heat loss, for example, by reducing the supplied voltage and the forward voltage (V) of the uLED. f The voltage difference between them. Unfortunately, a small but relevant anomalous uLED group can still exist with a forward voltage (V) f Excessively high (e.g., higher than the average forward voltage (V) of the uLED). f (20%, 25%, or a larger or smaller percentage, or a larger percentage in between).

[0026] One solution for providing sufficient power supply voltage includes providing all uLEDs on the die (including faulty uLEDs) with a voltage greater than (or equal to) the maximum voltage. f The power supply voltage. Using this solution, all uLEDs (including faulty uLEDs) will be driven correctly. However, as the voltage drop across the driver electronics will increase on average, heat loss will increase (reaching prohibitive levels in some practical cases).

[0027] Another solution involves ignoring abnormal uLEDs. Skipping these abnormal uLEDs allows the supply voltage to remain low, thus benefiting from the narrow forward voltage (V) between the uLEDs. f Deviation. In this solution, one or more V values ​​of the abnormal uLED are addressed by increasing the voltage source voltage. f Compared to other solutions, heat loss will be reduced. However, with such a solution, some abnormal uLEDs are likely to be undriven or underdriven. These undriven and / or underdriven uLEDs can appear as dark spots on the uLED array. In some applications, a large number of abnormal uLEDs may be unacceptable, especially if undriven and / or underdriven uLEDs remain visible.

[0028] Implementations may include (e.g., simple) driving schemes to provide voltage compliance for a faulty uLED driver, allowing the corresponding uLED to light up with minimal impact on heat loss or operating efficiency. The advantages provided by these implementations address one or more of the following challenges of driving pixelated matrix LEDs with linear driver schemes: (1) providing a cost-effective driving scheme for matrix uLEDs; (2) overcoming driver efficiency limitations; (3) overcoming voltage compliance limitations; or (4) addressing positive voltage deviations across pixel groups, where faulty uLEDs impair voltage compliance or driver efficiency.

[0029] In the embodiment, the abnormally high V f This can be a product of the dynamic series resistance of the uLED. Dynamic series resistance may be due to process tolerances that affect component quality, such as metal-semiconductor contacts. Based on these considerations, embodiments may include a current driver (uLED driver) that provides voltage compliance to a faulty uLED, which can then operate normally or be substantially lit (lit to an intensity within a specified lumen quantity or percentage, regardless of dynamic series resistance), with minimal impact on heat loss.

[0030] An embodiment may provide a uLED driver control technique in which abnormal pixels can be identified by means of sensing voltage (e.g., see...). Figure 9 This can be done during the uLED die assembly process or periodically (e.g., during diagnostic mode). An embodiment can provide a uLED driver control scheme, which can be used for those V f An abnormal uLED adjusts its pulse width modulation (PWM) current to a preset on-current value that indicates an excess of the average group's compliance voltage (e.g., exceeding a specified amount). This can be done during the uLED die assembly process or periodically (e.g., during diagnostic mode after uLED die fabrication).

[0031] The embodiment may provide a driver control technique in which the preset on-current value of the PWM current is reduced to the maximum PWM current (I0). PWM_MAX Below this, the V of the abnormal pixel is made f Fully reduced to V LED The following. This can cause the local uLED driver unit to enter a compliant voltage mode. An embodiment may provide a driver control technique in which the preset on-current value of the PWM current is reduced to I. PWM_MAX The following is the new value I PWM_0 This value is based on the series dynamic resistance (R0) between the abnormal uLED and the average group uLED. d The difference is approximately and / or partially estimated by means of different current levels (e.g., at target I). PWM_MAX Nearby (drive) pixels can be periodically characterized during the assembly process or during diagnostic mode. d R d It can be determined to be V fmax and V th (For example, see) Figure 10 The difference between I and I PWM R d rand can therefore be defined as [R dlow R dhigh ]. R dlow =(V fmax -V th ) / I PWM_MAX Similarly, R dhigh =(V fmax -V th ) / I PWM_0 Note that V th and I PWM_MAX Given by technical, design, and operating conditions. Fix them, V fmax (e.g., power supply voltage) and R d A direct relationship is thus established between them.

[0032] Figure 1 A schematic diagram of an embodiment of a uLED control system 100 is shown by way of example. The system 100 shown includes a voltage source 102 that supplies power, distributed by a plurality of LED drivers, to a uLED matrix 104. The voltage source 102 provides a constant direct current (DC) voltage V. LED 106 and constant reference voltage V GND 108. Voltage source 102 can fix the power supply voltage to V. LED The DC level is 106. This voltage does not change dynamically with the load line response (the load of the uLED array 104). Therefore, V LED106 does not change the dynamic changes during the pulse width modulation (PWM) period of the current driver signal.

[0033] As mentioned earlier, if V LED If 106 is set to account for anomalous pixels in the uLED array 104, then the heat loss in the uLED driver will be high (even alarmingly high). Conversely, if V LED 106 was set to V without considering abnormal uLEDs. f In this case, the abnormal uLED can remain undriven or underdriven. Such undriven or underdriven LEDs can appear as dark spots in the uLED matrix 104.

[0034] Figure 2 The example illustrates V without considering abnormal uLEDs. f This is a schematic diagram of an embodiment of a uLED array 200 driven under certain conditions. As can be seen, some uLEDs remain undriven or underdriven, resulting in black spots or darker spots 220 in the uLED array 200.

[0035] Figure 3 A schematic diagram of an embodiment of graph 300 illustrates, by way of example, the efficiency of the driver circuit versus the relative dynamic series resistance (as a percentage of all uLEDs in uLED array 200) of the abnormal uLED. As can be seen, the electrical efficiency of the driver circuit decreases as the dynamic resistance of the uLED considered abnormal increases. The goal could be to maintain an electrical efficiency greater than, for example, 85%, 80%, a larger or smaller percentage, or some percentage in between. Electrical efficiency is defined as power output divided by the power supplied. For example, if the abnormal uLED... d With a 20% increase in the total number of LEDs in uLED matrix 104, the driver efficiency drops from 86% (the baseline efficiency considering uLEDs without abnormalities) to 82%.

[0036] Figure 4 A logic block diagram of an embodiment of system 400 is shown by way of example. System 400 includes an electrical backplane electrically connected to uLED matrix 104. The electrical backplane includes uLED driver 444 and power supply circuitry. (About...) Figure 5 Further details are provided for a linear driver variant of the uLED driver 444. The power supply circuit includes V... LED 106 and the reference voltage V from the voltage source GND 108. V LED 106 is supplied to power layer 442. V GND 108 is provided to the ground plane 440. The uLED driver 444 uses V from the power plane 442. LED106 Power supply. The uLED driver 444 controls the individual uLEDs or groups of uLEDs in the uLED matrix 104 via electrical interconnects 446. The uLED driver 444 can control whether the uLEDs are turned on or off, and can control the duty cycle or other power control of the uLED 104.

[0037] The uLED matrix 104 is electrically coupled to the (corresponding) uLED driver 444 via electrical interconnect 446. The uLED matrix 104 is electrically coupled to ground plane 440 via other electrical interconnect 448. Dielectric 450 electrically and physically isolates the uLED driver 444 from ground plane 440. That is, dielectric 450 is (e.g., directly) located between the uLED driver 444 and ground plane 440, and (e.g., directly) located between ground plane 440 and power plane 442.

[0038] Figure 5 A logic circuit diagram of an embodiment of system 500 is shown by way of example. System 500 includes uLED driver 444 and uLED 550 in uLED matrix 104. uLED driver 444 controls electrical signal 554 on electrical interconnect 446. By controlling electrical signal 554, uLED driver 444 can suppress or allow current to flow to uLED 550. Using this control, uLED driver 444 can ultimately control whether and when individual uLED 550 or groups of uLED 550 are turned on, and can ultimately control the duty cycle of uLEDs.

[0039] To overcome the limitations of other uLED driving schemes and increase the electrical efficiency of the uLED matrix 104, several improved driving schemes are provided. The embodiments consider uLED dies with individually addressable pixels. The uLED die includes a uLED driver 444, which includes a linear driver architecture operating in PWM mode. By at least partially randomizing the phase of the pulse width modulation (PWM) control signal of the uLED, one or more control schemes can help minimize the total root mean square (RMS) and harmonic current driven by the voltage source 102.

[0040] The embodiment may include a voltage source 102, the output voltage of which can be supplied by a load with sufficient bandwidth response (e.g., a load controller 990 (see...)). Figure 9 Dynamic modulation and control. Embodiments may include a control scheme in which anomalous pixels can be identified (e.g., by means of sensed voltage) before or during the operation of the uLED matrix 104, and classified accordingly (see...). Figure 9During each or every few cycles of the driver's PWM signal, the controller 990 can increase the voltage from the voltage source 102 to act as the dynamic resistance (R) of the uLED. d The specified voltage value is a function of the voltage rating. Higher voltages can be specified as a function of the dynamic series resistance of the abnormal uLED.

[0041] An embodiment may include a control scheme that repeatedly (e.g., periodically, such as at predefined intervals) increases the power supply voltage to a specified voltage value during each or several cycles of the driver's PWM signal. The higher set voltage may be specified as the positive voltage (V0) of an abnormal pixel. f The forward voltage (V) of an LED is a function of 0. f () is the voltage drop across the LED when it is emitting light.

[0042] Embodiments may include a control scheme for changing the voltage to the uLED driver 444 of the uLED 550 and the current provided by the uLED driver 444 of the uLED 550. Embodiments may provide a control scheme that includes a modifiable set current for abnormal pixels.

[0043] Figure 6 A logic circuit diagram of an embodiment of system 600 is shown by way of example, which takes into account abnormal pixel R. d To drive the uLED matrix 104. System 600 is the same as or similar to uLED control system 100, wherein system 600 includes circuitry that provides control commands 660, which cause the R-based... d To uLED driver 444 (see Figure 4 The control command 660 can indicate the voltage or current based on the dynamic series resistance of a specific uLED 550 in the uLED matrix 104. The control command 660 indicates the voltage to be supplied to the uLED driver 444. The control command 660 can be issued by a controller 990 coupled to the uLED driver 444.

[0044] Controller 990 may include memory 988 (see Figure 9 ), or otherwise have the right to access a memory containing data indicating at least each having an abnormally high R d uLED's R d Duty cycle, PWM period, etc. The controller 990 can use this data to provide command 660, which causes the voltage of the uLED driver 444 to decrease, thereby reducing the current supplied by the uLED driver 444. The current can be set so that the forward voltage (V... f () less than the power supply voltage V LEDThe maximum value.

[0045] Figure 7 The dynamic series resistance (R) of multiple uLED matrix chips is illustrated by way of example. d Figure 700 shows an example of the distribution 774. One of the distributions 774 includes most uLEDs having R in the following three quartiles 770. d And R in the above quartile 772 d Abnormal uLEDs include abnormal R. d 776. Abnormal R d It can be defined according to R d The highest percentile (e.g., 75%, 80%, 85%, 90%, 95%, a larger percentage, or some percentage in between) of the uLEDs in the sorted uLED matrix 104, where the uLED in the uLED matrix 104 has an R value greater than a specified threshold. d (For example, at a specified percentile R) d R0 is the R0 of a specified number of standard deviations above the mean. d ,etc).

[0046] If V LED 106 is set to be based on R d The level of the specified percentile of the uLED coverage has anomalies R. d The 776 uLEDs 552 may be undriven or underdriven. As previously mentioned, this undriven or underdriven condition can lead to dark spots or other aberrations in the image produced by the uLED matrix 104.

[0047] Figure 8 A circuit diagram of an embodiment of a uLED pixel is shown by way of example (uLED 550 and corresponding uLED driver 444 (e.g., uLED driver 444 driving only a single uLED 550 or a small group of uLEDs (less than 10 uLEDs))). Figure 8 In circuit diagram 800, R is used depending on the uLED. d voltage V cs 880 to drive uLED driver 444. V cs 880 can come from the operator to provide various V cs 880-value circuits (e.g., trapezoidal resistors and multiplexers). Controller 990 can select the R corresponding to the uLED. d V cs 880, so that V f Reduce to V LED Below 106. Drive voltage (V) csThis reduction in the duty cycle of the uLED 550 decreases the drive current provided by the uLED driver 444. This decrease in drive current, in turn, leads to a reduction in the intensity of the uLED 550. The controller 990 can compensate for this reduction in intensity by increasing the duty cycle of the uLED 550.

[0048] Figure 9 The dynamic resistance (R) of a uLED in a uLED die is illustrated by way of example. d This is a schematic diagram of an embodiment of system 900. For the purpose of using the embodiment, and as discussed, controller 990 can be used as part of uLED matrix 104. Controller 990 may have access to memory 988 or include memory 988.

[0049] The memory 988 can store indicators of which uLEDs have abnormally high Ro. d (and the corresponding abnormally high V) f The data was used to determine whether the uLED 996 had an abnormally high R0. d Electrical stimulation 994 can be supplied to the uLED driver 444 via test device 992. Test device 992 may include a power source similar to voltage source 102. Test device 992 may be operable to change the amplitude, frequency, or other parameters of the current or voltage supplied as stimulation 994.

[0050] Stimulus 994 may include the voltage (V) used most of the time to drive uLED driver 444 LED 106). If sufficient responses 998 are detected, uLED 996 can be considered normal. If insufficient responses 998 are detected, uLED 996 can be considered abnormal. d .

[0051] In response to an insufficient response 998 (current below the expected (threshold) current), the test device 992 may store the identifier of the uLED 996 (e.g., by its position in the uLED matrix (such as by row and column) or other identifier) ​​in the memory 988 of the controller 990 (or a memory accessible by the controller 990). In this way, the controller 990 can determine when to drive the uLED with a reduced current using the uLED driver 444. Figure 9 One or more operations may be performed during manufacturing, after packaging, or during some other stage of manufacturing or distribution, or in combination thereof.

[0052] The controller 990 may include electrical or electronic components for performing its operation. These electrical or electronic components may include one or more transistors, resistors, capacitors, diodes, inductors, oscillators, switches, logic gates (e.g., AND, OR, XOR, NOT, buffers, etc.), multiplexers, analog-to-digital converters, digital-to-analog converters, amplifiers, rectifiers, modulators, demodulators, processors (e.g., central processing unit (CPU), graphics processing unit (GPU), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), etc.), memory devices (e.g., random access memory (RAM), read-only memory (ROM), etc.), and so on.

[0053] The driver 444 may include electrical or electronic components configured to supply power to one or more uLEDs in the uLED matrix 104 (sometimes referred to as uLED dies). These electrical or electronic components may include one or more transistors, resistors, capacitors, diodes, inductors, oscillators, switches, logic gates, multiplexers, analog-to-digital converters, digital-to-analog converters, amplifiers, rectifiers, modulators, demodulators, processors, memory devices, etc.

[0054] Figure 10 The example illustrates an anomaly R. d uLED and having lower R d The graph 1000 shows the current versus voltage of the uLED. The solid line 1010 corresponds to a normal R... d uLED, and the dashed line 1012 corresponds to the one with abnormal R. d uLED. As can be seen, the main difference between lines 1010 and 1012 is R. d (The reciprocal of the slopes of lines 1010 and 1012). In Figure 10 In this context, the threshold voltage 1022 (sometimes referred to as the bandgap) is the same or similar for uLEDs, assuming they all operate at the same temperature (note that this is not a necessary condition, and the Vt of uLEDs is also different). th (Can be different). When the same on-state current I PWM_MAX When driving these uLEDs, the forward voltage difference is V. f0 1018-V fmax 1020. This difference is due to R in uLED. d It is determined by differences.

[0055] The embodiment reduces the current driving abnormal pixels to current level I. PWM_0 1016. At a lower current level I PWM_0 1016 drives the abnormal pixel, causing the voltage of the abnormal pixel to change from V. f0 Drop to compliance voltage V fmax Vfmax Corresponding to the maximum V generated by voltage source 102 LED .

[0056] exist Figure 8 In the driver schematic, this is achieved by making the control voltage V cs For R d This is achieved through a function. V cs It controls the current supplied to the uLED (I) PWM The voltage signal.

[0057] In the latest linear current drivers used for LED arrays, V cs It is constant and substantially the same across all LEDs. In contrast, embodiments allow for variations in R. d The uLEDs (e.g., for each uLED) are set with V differently. cs This forces the PWM on-state current (I0) to... PWM (Below I) PWM_MAX (in response to the use of V) LED The driver current generated when driving the uLED driver 444. Figure 10 The lower current shown is I PWM_0 1016. V Based on the change in power supply voltage, cs The new value makes it have anomalies R d The forward voltage (V) of the uLED f It can be reduced to make it lower than V. LED .

[0058] Figure 11 Graph 1100 illustrates the peak driver current (%) versus the dynamic series resistance of the uLED by way of example. To achieve this, there is detection of abnormal uLEDs, and selective reduction of V based on said detection. cs The process. Figure 11 R is shown in d A quasi-linear relationship exists between the required local reduction of the PWM on-state current and the voltage. This establishes the maximum current capability applied to abnormal pixels to avoid V... LED (And therefore the driver loss) increases above the group identified as the driving average pixel group. For example, according to Figure 11 R relative to the average population d The 30% increase resulted in an approximately 23% reduction in the PWM on-state current of the abnormal uLED. In the absence of this recommended measure, to help ensure the uLED is supplied with sufficient current, the supply voltage V... LED 106 can be based on R d It increases with the corresponding driver current.

[0059] Figure 12 V is illustrated through examples. LED 106 and those with abnormal R d The graph 1200 shows the relative dynamic resistance of the uLEDs. If followed by the controller 990, this graph helps ensure that the driver voltage is compliant with all uLEDs (including abnormal uLEDs). The corresponding efficiency loss is... Figure 3 As shown in the solid line. If the solution of the embodiment is used, the efficiency remains independent of the forward voltage (V). f ), such as by Figure 3 The dotted line indicates this.

[0060] Aberrant uLEDs limited by the recommended peak current can remain correctly driven, provided there is sufficient time margin for duty cycle correction (increasing the duty cycle in response to a decrease in the PWM on-state current). The number of underdriven aberrant uLEDs depends on the target light distribution and the specific uLED die. A typical light distribution in the application corresponds to a non-uniform light pattern (a light pattern with non-uniform colors). Therefore, a large number of uLEDs are expected to operate at duty cycles that can be corrected in response to a decrease in the driver current (e.g., at low or medium duty cycle levels). Given such a distribution, it is statistically possible to estimate how many undriven and underdriven pixels can be represented as R d A function for the number of abnormal uLEDs was found.

[0061] Figure 13 A schematic diagram of an embodiment of a method 1300 for driving a uLED matrix die is shown by way of example. Method 1300 can be performed at least in part by a voltage source 102, a uLED matrix 104, a controller 990, a driver 444, other components, or a combination thereof. As shown, method 1300 includes, in operation 1302, identifying the dynamic series resistance (R0) of the uLEDs in the uLED die by the controller of the micro-light-emitting diode (uLED) die. d ) or positive voltage (V f In operation 1304, by the controller and based on the identified R d or V f To select a current level less than the maximum current level provided by the uLED driver coupled to the uLED die (I PWM_MAX The current level (I) PWM_0 In operation 1306, the controller supplies current to the uLED driver at a selected current level.

[0062] Method 1300 may further include responding to selection I PWM_0The pulse width modulation (PWM) on-time of the uLED is increased by the controller. Method 1300 may further include testing each uLED in the uLED die with a test device to determine whether the uLED includes an R value greater than a specified threshold. d or V f Method 1300 may further include storing data in a memory accessible by the controller of the uLED die, the data indicating that the uLED die includes R greater than a specified threshold. d Each uLED has an identifier (ID). Method 1300 may further include an identifier based on the R... d Determine I PWM_0 This makes the V of uLED f Less than (or equal to) the maximum supply voltage (V) LED ).

[0063] Method 1300 may further include, wherein the controller is an LED die containing an R value greater than a specified threshold. d or V f Each uLED selects I PWM_0 Method 1300 may further include, wherein the specified threshold is the R of all uLEDs across the uLED die. d or V f The specified percentile of the value. Method 1300 may further include, wherein the R value is based on the abnormal uLED in the uLED die. d or V f The average R of non-abnormal uLEDs d or V f The difference between them is chosen to be less than the maximum current level (I) provided by the uLED driver coupled to the uLED die. PWM_MAX The current level (I) PWM_0 The abnormal uLED includes R values ​​greater than a specified number of standard deviations. d The specified number of standard deviations is greater than the average R of the uLED. d or V f .

[0064] The following are some details about the uLED matrix 104 and some application considerations, followed by some examples.

[0065] Figure 14 More detailed support is shown for, for example, relative to Figures 6-13 An embodiment of a chip-level implementation of the system 1400 with the functions discussed. System 1400 includes a command and control module 1416 (sometimes referred to as a controller, which can be connected to...) Figure 9 (Similar to or the same as) the controller 990, the command and control module 1416 is capable of providing commands such as those relative to... Figures 6-13The circuitry and processes discussed elsewhere in this document implement pixel- or group-pixel-level control of amplitude and duty cycle. In some embodiments, system 1400 also includes a frame buffer 1410 for storing generated or processed images that can be supplied to the matrix 1420 of the uLED. Other modules may include digital control interfaces configured to transmit control data or instructions or response data, such as a serial bus (e.g., an internal integrated circuit (I... 2 C) Serial bus or Serial Peripheral Interface (SPI) (1414).

[0066] In operation, system 1400 can receive images or other data arriving via SPI interface 1414 from a vehicle or other source. Continuous image or video data can be stored in image frame buffer 1410. If no image data is available, one or more backup images stored in backup image buffer 1411 can be routed to image frame buffer 1410. Such backup images may include, for example, intensity and spatial patterns consistent with legally permitted low-beam headlight radiation patterns for vehicles, or default light radiation patterns used for architectural lighting or displays.

[0067] In operation, pixels in the image are used to define the response of the corresponding active LED pixels, where the intensity and spatial modulation of the LED pixels are based on the image(s). To reduce data rate issues, in some embodiments, pixel groups (e.g., 5×5 blocks) can be controlled as a single block. In some embodiments, high-speed and high-data-rate operation is supported, where pixel values ​​from successive images can be loaded as consecutive frames in an image sequence at a rate between 30Hz and 100Hz—with 60Hz being typical. PWM can be used to control each pixel to emit light in a manner at least in part dependent on the pattern and intensity of the image stored in the image frame buffer 1410.

[0068] In some embodiments, system 1400 can be via V dd and V ss The pins receive logic power. The active matrix receives power through multiple V... LED and V CathodeThe pins provide power for LED array control. The SPI 1414 can provide full-duplex communication using a master-slave architecture with a single master device. The master device initiates frames for reading and writing. Multiple slave devices are supported by selection using individual slave select (SS) lines. Input pins may include Master Output Slave Input (MOSI), Master Input Slave Output (MISO), Chip Select (SC), and Clock (CLK), all of which connect to the SPI interface 1414. The SPI interface 1414 connects to an address generator, frame buffer, and spare frame buffer. Pixels can be parameterized and have their signal or power modified via command and control modules, such as power gating before input to the frame buffer or pulse width modulation or power gating after output from the slave frame buffer. The SPI interface 1414 can connect to an address generation module 1418, which in turn provides row and address information to the active matrix 1420. The address generation module 1418 can then provide frame buffer addresses to the frame buffer 1410.

[0069] In some embodiments, the command and control module 1416 can be externally controlled via a serial bus 1412. It may support pins such as a clock (SCL) pin and a data (SDA) pin with 7-bit addressing. The command and control module 1416 may include a digital-to-analog converter (DAC) and two analog-to-digital converters (ADCs). The DAC and ADCs are used to set V for the connected active matrix, respectively. bias Help determine the maximum V f The system temperature is determined. An oscillator (OSC) is also connected to set the pulse-width modulation oscillation (PWMOSC) frequency of the active matrix 1420. In one embodiment, a bypass path is also provided to allow addressing of individual pixels or pixel blocks in the active matrix for diagnostic, calibration, or testing purposes. The active matrix 1420 may be further supported by row and column selection for addressing individual pixels, which are supplied with data lines, bypass paths, PWMOSC lines, V... bias Line and V f Wire.

[0070] As those skilled in the art will understand, in some embodiments, the described circuitry and active matrix 1420 may be packaged and optionally include a base or printed circuit board for powering and controlling the light generated by the semiconductor LEDs. In some embodiments, the printed circuit board may also include electrical vias, heat sinks, ground planes, electrical traces, and flip chips, or other mounting systems. The base or printed circuit board may be formed of any suitable material, such as ceramic, silicon, aluminum, etc. If the base material is conductive, an insulating layer is formed over the substrate material, and a pattern of metal electrodes is formed over the insulating layer. The base may act as a mechanical support, provide an electrical interface between the electrodes and power supply on the LEDs, and also provide heat dissipation.

[0071] In some embodiments, the active matrix 1420 can be formed from light-emitting elements of various types, sizes, and layouts. In one embodiment, a one-dimensional or two-dimensional matrix array of individually addressable light-emitting diodes (LEDs) can be used. Typically, an N×M array can be used, where N and M are between two and one thousand, respectively. Individual LED structures can have square, rectangular, hexagonal, polygonal, circular, arcuate, or other surface shapes. The array of LED components or structures can be arranged in geometrically straight rows and columns, staggered rows or columns, curved lines, or a semi-random or random layout. LED components can include multiple LEDs, and these LEDs can also be formed as an array of individually addressable pixels. In some embodiments, radial or other non-rectangular grid arrangements of the conductors to the LEDs can be used. In other embodiments, bent, wound, meandering, and / or other suitable non-linear arrangements of the conductive lines to the LEDs can be used.

[0072] In some embodiments, an array of microLEDs (μLEDs or uLEDs) can be used. uLEDs can support high-density pixels with a lateral dimension of less than 100 μm by 100 μm. In some embodiments, uLEDs with a diameter or width of approximately 50 μm or less can be used. Such uLEDs can be used to fabricate color displays by closely arranging uLEDs including red, blue, and green wavelengths. In other embodiments, uLEDs can be defined on a monolithic gallium nitride (GaN) or other semiconductor substrate, formed on segmented, partially or completely separate semiconductor substrates, or formed individually or assembled into groups of uLEDs. In some embodiments, an active matrix (uLED matrix 104) can include a small number of uLEDs located on a substrate with an area of ​​centimeters or larger. In some embodiments, an active matrix 1420 can support an array of uLED pixels with hundreds, thousands, or millions of LEDs located together on a substrate with an area of ​​centimeters or smaller. In some embodiments, uLEDs can include LEDs with a size between 30 micrometers and 500 micrometers. In some embodiments, each emitting pixel in the emitting pixel array can be positioned at least 1 millimeter apart to form a sparse LED array. In other embodiments, the sparse LED array of light-emitting pixels can be positioned with a spacing of less than 1 millimeter and a distance ranging from 30 micrometers to 500 micrometers. The LEDs can be embedded in a solid or flexible substrate, which can be at least partially transparent. For example, the light-emitting pixel array can be at least partially embedded in glass, ceramic, or polymeric materials.

[0073] Emitting pixel arrays, such as those discussed herein, can support applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This can include, but is not limited to, precise spatial patterning of light emitted from pixel blocks or individual pixels. Depending on the application, the emitted light can be spectrally distinct, time-adaptive, and / or environmentally responsive. Emitting pixel arrays can provide pre-programmed light distributions in various intensity, spatial, or temporal patterns. The emitted light can be based at least in part on received sensor data and can be used for optical wireless communication. The associated optics can be distinct at the pixel, pixel block, or device level. Example emitting pixel arrays may include devices with a central block of high-intensity pixels that share associated common optics, while edge pixels may have individual optics. Common applications supported by emitting pixel arrays include video lighting, automotive headlights, architectural and area lighting, street lighting, and information displays.

[0074] Emitting pixel arrays can be used to selectively and adaptively illuminate buildings or areas to improve visual presentation or reduce lighting costs. Additionally, emitting pixel arrays can be used to project onto media facades for decorative motion or video effects. Combined with tracking sensors and / or cameras, selectively illuminating areas around pedestrians is possible. Pixels with distinctly different spectra can be used to adjust the color temperature of the lighting, as well as to support garden lighting at specific wavelengths.

[0075] Street lighting is an application that can benefit from the use of emitting pixel arrays. A single emitting array can be used to simulate various street light types, allowing switching between Type I linear streetlights and Type IV semi-circular streetlights, for example, by appropriately activating or deactivating selected pixels. Additionally, street lighting costs can be reduced by adjusting the beam intensity or distribution based on environmental conditions or usage time. For example, when there are no pedestrians, the light intensity and distribution area can be reduced. If the pixels in the emitting pixel array are spectrally distinct, the color temperature of the light can be adjusted according to the corresponding daytime, dusk, or nighttime conditions.

[0076] Illuminated arrays are also suitable for applications requiring direct or projected displays. For example, warnings, emergency signals, or information signs can be displayed or projected using illuminated arrays. This allows for the projection of, for example, color-changing or flashing exit signs. If the illuminated array consists of a large number of pixels, it can display text or numerical information. Directional arrows or similar indicators can also be provided.

[0077] Vehicle headlights are an application requiring a large number of pixels and a high data refresh rate for the light-emitting array. Motor vehicle headlights that actively illuminate only selected sections of the road can reduce problems associated with glare or blindness to oncoming drivers. Using an infrared camera as a sensor, the light-emitting pixel array activates only those pixels needed to illuminate the road, while deactivating pixels that might glare pedestrians or oncoming vehicles. Additionally, pedestrians, animals, or signs outside the road can be selectively illuminated to improve the driver's environmental awareness. If the pixels in the light-emitting pixel array are spectrally distinct, the color temperature of the light can be adjusted according to the corresponding daytime, dusk, or nighttime conditions. Some pixels can be used for optical wireless vehicle-to-vehicle communication.

[0078] LED light modules can include individual LEDs or matrix LEDs combined with primary or secondary optics (including lenses or mirrors). To reduce overall data management requirements, the light module may be limited to on / off functionality or switching between relatively few light intensity levels. Full pixel-level control of light intensity is not necessarily supported.

[0079] In operation, pixels in an image are used to define the response of the corresponding LED pixel in a pixel module, where the intensity and spatial modulation of the LED pixel are based on the image(s). To reduce data rate issues, in some embodiments, pixel groups (e.g., 5×5 blocks) can be controlled as a single block. High-speed and high-data-rate operation is supported, where pixel values ​​from consecutive images can be loaded as consecutive frames in an image sequence at rates between 30Hz and 100Hz (where 60Hz is a typical rate). Combined with a pulse width modulation module, each pixel in the pixel module can be operated to emit light at a mode and intensity at least in part depending on the image stored in the image frame buffer.

[0080] In the foregoing embodiments, the intensity of a uLED can be individually controlled and adjusted by setting appropriate ramp time and pulse width for each LED pixel using suitable lighting logic, control modules, and / or PWM modules. Abnormal pixel voltage management can provide LED pixel activation to deliver reliable patterned lighting. Figure 15 The diagram shows a control system 1500 that can provide voltage management for voltage source 102. For example, in... Figure 15 As seen in the diagram, the matrix microLED array 1520 can comprise one or more arrays of thousands to millions of microLED pixels, which actively emit light and are individually controlled. To emit light in a pattern or sequence that results in an image display, the current level of the microLED pixels at different locations on the array is individually adjusted according to the specific image. This can involve PWM, which turns the pixels on and off at a specific frequency. During PWM operation, the average DC current through the pixel is the product of the current amplitude and the PWM duty cycle, which is the ratio between the on-time and the period or cycle time.

[0081] Figure 15 A logic block diagram of system 1500 is shown by way of example. System 1500 includes circuitry that can be contained in a uLED package. Figure 15 The diagram illustrates a processing module that facilitates the effective use of system 1500. System 1500 includes a control module 1516, which is capable of handling tasks such as... Figures 6-14 The circuitry and programming discussed implement pixel- or group-pixel-level control of amplitude and duty cycle. In some embodiments, system 1500 further includes an image processing module 1504 for generating, processing, or transmitting images, and a digital control interface 1513 configured to transmit control data and / or instructions, such as an internal integrated circuit (I... 2C) Serial Peripheral Interface (SPI), Controller Area Network (CAN), Universal Asynchronous Receiver / Transmitter (UART), etc. The digital control interface 1513 and control module 1516 may include a system microcontroller and any type of wired or wireless module configured to receive control input from external devices. By way of example, the wireless module may include Bluetooth, Zigbee, Z-Wave, Mesh, WiFi, Near Field Communication (NFC), and / or peer modules may be used. The microcontroller may be any type of dedicated computer or processor that can be embedded in the LED lighting system and is configured or configurable to receive input from wired or wireless modules or other modules in the LED system, and based on this, provide control signals to other modules. Algorithms implemented by the microcontroller or other suitable control module 1516 may be implemented in a computer program, software, or firmware incorporating a non-transitory computer-readable storage medium for execution by a dedicated processor. Examples of non-transitory computer-readable storage media include read-only memory (ROM), random access memory (RAM), registers, cache memory, and semiconductor memory devices. The memory can be included as part of the microcontroller, or it can be implemented elsewhere, on or off a printed circuit board or electronic board.

[0082] As used herein, the term "module" can refer to electrical and / or electronic components mounted on a separate circuit board that can be soldered to one or more electronic boards. However, the term "module" can also refer to electrical and / or electronic components that provide similar functionality but can be individually soldered to one or more circuit boards in the same or different areas.

[0083] The control module 1516 (similar to or the same as controller 990) may further include an image processing module 1504 and a digital control interface 1513 (such as I...). 2 C). As will be appreciated, in some embodiments, image processing calculations may be performed by control module 1516 by directly generating a modulated image. Alternatively, standard image files may be processed or otherwise converted to provide modulation that matches the image. Image data, primarily consisting of PWM duty cycle values, may be processed for all pixels in image processing module 1504. Since the amplitude is a fixed or rarely changing value, amplitude-related commands can be transmitted via a simpler digital interface (such as I...). 2 C) Provided separately. The control module 1516 interprets the digital data, which can be used by the PWM generator 1510 to generate PWM signals for the pixels and by the digital-to-analog converter (DAC) 1512 to generate control signals for obtaining the desired current source amplitude.

[0084] In some embodiments, Figure 15The matrix micro-LED array 1520 may include m pixels, each comprising m common anode LEDs. In one example embodiment, a pixel unit includes a single LED (LED1) and three transconductance devices (MOSFET switches) M1 to M3, and is powered by a voltage source V1 (sometimes referred to as V). LED Power supply. M3 is an N-channel metal-oxide-semiconductor field-effect transistor (MOSFET) whose gate is coupled to an amplitude control signal to generate the required current source amplitude. A P-channel MOSFET M1 is connected in parallel with LED1 and forms a totem pair with the N-channel MOSFET M2. The gates of the M1 and M2 transistor pair are connected together and coupled to the PWM signal. Therefore, when PWM is high, M1 will be off and M2 will be on. Current will flow through LED1, M2, and M3, the value of which is determined by the amplitude control signal coupled to the gate of M3. When PWM is low, M1 will be on and M2 will be off. Therefore, the current source of M3 will be cut off, and the LED will discharge rapidly through M1.

[0085] Figure 16 A block diagram of an embodiment of a machine 1600 (e.g., a computer system) for implementing one or more embodiments is shown by way of example. Machine 1600 may implement techniques for managing under-driving or undriven uLEDs in uLED dies. Controller 990, test device 992, voltage source 102, or components thereof may include one or more components of machine 1600. One or more of controller 990, test device 992, voltage source 102, or components thereof may be implemented using at least partially components of machine 1600. An example machine 1600 (in the form of a computer) may include a processing unit 1602, memory 1603, removable storage 1610, and non-removable storage 1612. Although an example computing device is shown and described as machine 1600, the computing device may take different forms in different embodiments. For example, the computing device may instead be a smartphone, tablet, smartwatch, or include components related to… Figure 16 Other computing devices with the same or similar elements shown and described. Devices such as smartphones, tablets, and smartwatches are generally referred to as mobile devices. Furthermore, although various data storage elements are shown as part of machine 1600, this storage may also include, or alternatively may include, cloud-based storage accessible via a network such as the Internet.

[0086] Memory 1603 may include volatile memory 1614 and non-volatile memory 1608. Machine 1600 may include, or have access to, a computing environment including various computer-readable media such as volatile memory 1614 and non-volatile memory 1608, removable storage 1610, and non-removable storage 1612. Computer storage includes random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, optical disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices capable of storing computer-readable instructions for performing the functions described herein.

[0087] Machine 1600 may include or have access to a computing environment including input 1606, output 1604, and communication connection 1616. Output 1604 may include a display device (such as a touchscreen), which may also be used as an input device. Input 1606 may include a touchscreen, touchpad, mouse, keyboard, camera, one or more device-specific buttons, one or more sensors integrated into machine 1600 or coupled to machine 1600 via a wired or wireless data connection, and one or more other input devices. The computer may operate in a networked environment using the communication connection to connect to one or more remote computers (such as database servers, including cloud-based servers and storage). Remote computers may include personal computers (PCs), servers, routers, network PCs, peer-to-peer devices, or other common network nodes. The communication connection may include a local area network (LAN), a wide area network (WAN), cellular, or IEEE 802.11. Or other networks.

[0088] Computer-readable instructions stored on a computer-readable storage device can be executed by a processing unit 1602 (sometimes referred to as processing circuitry) of machine 1600. Hard disk drives, CD-ROMs, and RAM are some examples of articles that include non-transitory computer-readable media such as storage devices. For example, computer program 1618 can be used to cause processing unit 1602 to execute one or more methods or algorithms described herein. Non-transitory does not mean incapable of being in motion (incapable of being in transport).

[0089] To further illustrate the apparatus and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples may exist independently or may be combined with any one or more of the other examples in any permutation or combination.

[0090] In Example 1, one method includes: identifying the dynamic series resistance (R0) of the uLED in the uLED die by a controller of the uLED die. d ) or positive voltage (V f ), by the controller and based on the identified R d or V f To select a current level less than the maximum current level provided by the uLED driver coupled to the uLED die (I PWM_MAX The current level (I) PWM_0 ), and the controller supplies current to the uLED driver at a selected current level.

[0091] In Example 2, Example 1 may further include a response to selection I PWM_0 The controller increases the pulse width modulation (PWM) on-time of the uLED.

[0092] In Example 3, at least one of Examples 1-2 may further include testing each uLED in the uLED die with a test device to determine whether the uLED includes an R value greater than a specified threshold. d or V f .

[0093] In Example 4, Example 3 may further include storing data in a memory accessible by the controller of the uLED die, the data indicating that the uLED die includes R greater than a specified threshold. d Each uLED has an identifier (ID).

[0094] In Example 5, Example 4 can further include based on the identified R d Determine I PWM_0 This makes the V of uLED f Less than (or equal to) the maximum supply voltage (V) LED ).

[0095] In Example 6, at least one of Examples 3-5 may further include, wherein the controller comprises an R in the uLED die greater than a specified threshold. d or V f Each uLED selects I PWM_0 .

[0096] In Example 7, at least one of Examples 3-6 may further include, wherein the specified threshold is R of all uLEDs across the uLED die. d or V f The specified percentile of the value.

[0097] In Example 8, according to at least one of Examples 1-7, wherein the R based on the abnormal uLED in the uLED die...d or V f The average R of non-abnormal uLEDs d or V f The difference between them is chosen to be less than the maximum current level (I) provided by the uLED driver coupled to the uLED die. PWM_MAX The current level (I) PWM_0 The abnormal uLED includes R values ​​greater than a specified number of standard deviations. d The specified number of standard deviations is greater than the average R of the uLED. d or V f .

[0098] Example 9 may include a system comprising: a micro light-emitting diode (uLED) die including a uLED and a corresponding uLED driver; a power supply coupled to the uLED die; and a controller coupled to the uLED die, the controller being configured to: identify a dynamic series resistance (R0) of the uLED in the uLED die. d ) or positive voltage (V f Based on the identified R d or V f To select a current level less than the maximum current level provided by the uLED driver of the uLED die (I PWM_MAX The current level (I) PWM_0 ), and to supply current to the uLED driver at the selected current level.

[0099] In Example 10, Example 9 may further include, wherein the controller is further configured to respond to selection I PWM_0 Increase the pulse width modulation (PWM) turn-on time of uLED.

[0100] In Example 11, at least one of Examples 9-10 may further include a test device configured to test each uLED in the uLED die to determine whether the uLED includes an R greater than a specified threshold. d or V f .

[0101] In Example 12, Example 11 may further include a memory accessible by the controller of the uLED die to store data indicating that the uLED die includes R greater than a specified threshold. d Each uLED has an identifier (ID).

[0102] In Example 13, Example 12 may further include, wherein the controller is also configured to be based on the identified R d Determine I PWM_0 This makes the V of uLED f Less than (or equal to) the maximum supply voltage (V)LED ).

[0103] In Example 14, at least one of Examples 11-13 may further include, wherein the controller comprises an R in the uLED die that is greater than a specified threshold. d or V f Each uLED selects I PWM_0 .

[0104] Example 15 includes a machine-readable medium comprising instructions that, when executed by a machine, cause the machine to perform an operation including: identifying a dynamic series resistance (R) of a microlight-emitting diode (uLED) in a uLED die. d ) or positive voltage (V f Based on the identified R d or V f To select a current level less than the maximum current level provided by the uLED driver of the uLED die (I PWM_MAX The current level (I) PWM_0 ), and to supply current to the uLED driver at the selected current level.

[0105] In Example 16, Example 15 may further include, wherein the operation also includes responding to selection I PWM_0 The controller increases the pulse width modulation (PWM) on-time of the uLED.

[0106] In Example 17, at least one of Examples 15-16 may further include, wherein the operation further includes testing each uLED in the uLED die to determine whether the uLED includes an R greater than a specified threshold. d or V f .

[0107] In Example 18, Example 17 may further include, wherein the operation further includes storing data in a memory indicating that the uLED die contains R greater than a specified threshold. d Each uLED has an identifier (ID).

[0108] In Example 19, at least one of Examples 17-18 may further include, wherein the specified threshold is R of all uLEDs across the uLED die. d or V f The specified percentile of the value.

[0109] In Example 20, at least one of Examples 15-19 may further include, wherein the R based on the abnormal uLED in the uLED die d or V f The average R of non-abnormal uLEDsd or V f The difference between them is chosen to be less than the maximum current level (I) provided by the uLED driver coupled to the uLED die. PWM_MAX The current level (I) PWM_0 The abnormal uLED includes R values ​​greater than a specified number of standard deviations. d The specified number of standard deviations is greater than the average R of the uLED. d or V f .

[0110] While exemplary embodiments of the subject matter of this disclosure have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many variations, modifications, and substitutions will now occur to those skilled in the art upon reading and understanding the material provided herein, without departing from the disclosed subject matter. It should be understood that various alternatives to the embodiments of the subject matter disclosed herein may be employed in practicing the various embodiments of this subject matter. It is intended that the following claims define the scope of the disclosed subject matter and thereby cover the methods and structures within the scope of these claims and their equivalents.

Claims

1. A method for controlling a light-emitting device, comprising: Data is stored in a memory accessible by a controller of a uLED die, the data indicating an identification of each uLED in the uLED die that includes a dynamic series resistance (R d ) greater than a specified threshold. for each uLED included in the uLED die that includes a dynamic series resistance (R d ) greater than a specified threshold, selecting, by the controller and based on the identified R d , a current level (I PWM_0 ) that is less than a maximum current level (I PWM_MAX ) provided by a uLED driver coupled to the uLED die; and The controller supplies current to the uLED driver at a selected current level.

2. The light-emitting device control method according to claim 1, further comprising responding to selection I PWM_0 The controller increases the pulse width modulation (PWM) on-time of the uLED.

3. The light-emitting device control method according to claim 1 further includes testing each uLED in the uLED die with a testing device to determine whether the uLED includes an R value greater than the specified threshold. d .

4. The light-emitting device control method according to claim 3, wherein electrical stimulation is provided to the uLED driver through the test equipment to determine whether the uLED has an abnormally high dynamic series resistance (R0). d ).

5. The light-emitting device control method according to claim 4, further comprising controlling the light-emitting device based on the identified R. d Determine I PWM_0 This makes the forward voltage (V) of the uLED... f () Less than (or equal to) the maximum power supply voltage (V) LED ).

6. The light-emitting device control method according to claim 3, wherein it is determined whether the uLED includes a dynamic series resistance (R) greater than the specified threshold. d This is done during the assembly process or operation of the uLED die.

7. The light-emitting device control method according to claim 3, wherein the specified threshold is the R value across all uLEDs in the uLED die. d The specified percentile of the value.

8. The light-emitting device control method according to claim 1, wherein the R based on the abnormal uLED in the uLED die... d The average R of non-abnormal uLEDs d The difference between them is chosen to be less than the maximum current level (I) provided by the uLED driver coupled to the uLED die. PWM_MAX The current level (I) PWM_0 The abnormal uLED includes R values ​​greater than a specified number of standard deviations. d The specified number of standard deviations is greater than the average R of the uLED. d .

9. A control system for a light-emitting device, comprising: A micro light-emitting diode (uLED) die, which includes a uLED and a corresponding uLED driver; Power supply coupled to the uLED die; A memory accessible by the controller of the uLED die to store data indicating that the uLED die includes a dynamic series resistance (R) greater than a specified threshold. d The identifier for each uLED; and A controller coupled to the uLED die, the controller being configured to: The dynamic series resistance (R) of the uLED in the uLED die is identified. d ); For the uLED die containing a dynamic series resistance (R) greater than the specified threshold... d For each uLED, select one with a current level less than the maximum current level (I) provided by the uLED driver of the uLED die. PWM_MAX The current level (I) PWM_0 );and The power supply provides current to the uLED driver at the selected current level.

10. The light-emitting device control system of claim 9, wherein the controller is further configured to respond to selection I PWM_0 Increase the pulse width modulation (PWM) turn-on time of the uLED.

11. The light-emitting device control system of claim 9, further comprising a testing device configured to test each uLED in the uLED die to determine whether the uLED includes an R value greater than the specified threshold. d .

12. The light-emitting device control system of claim 9, wherein the controller is further configured to be based on the identified R d Determine I PWM_0 This makes the forward voltage (V) of the uLED... f () Less than (or equal to) the maximum power supply voltage (V) LED ).

13. A machine-readable medium including instructions that, when executed by a machine, cause the machine to perform operations, the operations including: Data is stored in a memory accessible by the controller of the uLED die, the data indicating that the uLED die includes a dynamic series resistance (R) greater than a specified threshold. d The identifier for each uLED; For the uLED die containing a dynamic series resistance (R) greater than the specified threshold... d For each uLED, select one with a current level less than the maximum current level (I) provided by the uLED driver of the uLED die. PWM_MAX The current level (I) PWM_0 );and The power supply provides current to the uLED driver at the selected current level.

14. The machine-readable medium of claim 13, wherein the operation further includes responding to selection I PWM_0 The controller increases the pulse width modulation (PWM) on-time of the uLED.

15. The machine-readable medium of claim 13, wherein the operation further comprises testing each uLED in the uLED die to determine whether the uLED includes an R value greater than the specified threshold. d .

16. The machine-readable medium of claim 15, wherein electrical stimulation is provided to the uLED driver via a test device to determine whether the uLED has an abnormally high dynamic series resistance (Ro). d ).

17. The machine-readable medium of claim 15, wherein the specified threshold is the Ri of all uLEDs across the uLED die. d The specified percentile of the value.

18. The machine-readable medium of claim 13, wherein the R based on the abnormal uLED in the uLED die... d The average R of non-abnormal uLEDs d The difference between them is chosen to be less than the maximum current level (I) provided by the uLED driver coupled to the uLED die. PWM_MAX The current level (I) PWM_0 The abnormal uLED includes R values ​​greater than a specified number of standard deviations. d The specified number of standard deviations is greater than the average R of the uLED. d .

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