Dynamic brightness control of light-emitting diode arrays

Abstract

To provide a suitable dynamic brightness control for a light-emitting diode array. [Solution] The device includes a light-emitting diode (LED) driver circuit, one or more LEDs in an LED array, and an electronic switching circuit. The LED driver circuit is configured to generate current. One or more LEDs are electrically connected to the LED driver circuit. The electronic switching circuit is electrically connected to one or more LEDs and is configured to be installed in one of a plurality of switching configurations. The electronic switching circuit is further configured to direct a portion of the current away from one or more LEDs so that the remainder of the current drives one or more LEDs. A portion of the current corresponds to one of a plurality of switching configurations.

Description

TECHNICAL FIELD

[0001] (Cross-Reference to Related Applications) This application claims the priority benefit of U.S. Application No. 62 / 950,324, filed on December 19, 2019, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates to methods and apparatuses for controlling dynamic brightness of light emitting diode (LED) arrays, such as electronic displays or LED lighting systems.

BACKGROUND ART

[0003] Conventional lighting controller circuits used to drive electronic displays and other lighting systems sometimes provide a relatively narrow range of brightness. A narrow range of brightness can affect user experience, particularly when projecting light under dark ambient light conditions where a lower overall brightness is desired. Furthermore, an excessively bright electronic display or other lighting system can increase power consumption and increase the visibility of optical artifacts.

SUMMARY OF THE INVENTION

MEANS FOR SOLVING THE PROBLEMS

[0004] Innovative aspects of the subject matter described in the present specification include methods and apparatuses for controlling a light emitting diode (LED) array. An apparatus for controlling an LED array includes an LED driver circuit, one or more LEDs of the LED array, and an electronic switching circuit. The LED driver circuit is configured to generate an electric current. The one or more LEDs are electrically connected to the LED driver circuit. The electronic switching circuit is electrically connected to the one or more LEDs and is configured to be placed in one of a plurality of switching configurations. The electronic switching circuit is further configured to direct a portion of the electric current away from the one or more LEDs, such that the remaining portion of the electric current drives the one or more LEDs. The portion of the electric current corresponds to one of the plurality of switching configurations.

[0005] Innovative aspects of the subject matter described herein further include methods and apparatus for controlling an LED array. The apparatus for controlling an LED array includes one or more LEDs in the LED array, a first programmable LED driver circuit electrically connected to one or more LEDs, and a second programmable LED driver circuit electrically connected to one or more LEDs. The first programmable LED driver circuit is configured to be installed in one of a first set of configurations. The first programmable LED driver circuit is further configured to generate a first current corresponding to one of the first set of configurations. The second programmable LED driver circuit is configured to be installed in a second of a second set of configurations. The second programmable LED driver circuit is further configured to generate a second current corresponding to a second of the second set of configurations. The first and second currents are combined to form a third current to drive one or more LEDs.

[0006] Among the benefits and advantages, the embodiments disclosed herein increase the dynamic brightness range of a red-green-blue (RGB) LED array compared to conventional methods by reducing the minimum brightness limit of the LEDs powered by the LED driver circuit. The embodiments provide an improved user experience for users of RGB displays, particularly under dim lighting conditions. The embodiments also enable lower power consumption compared to conventional LED controllers by extending the dynamic range of display brightness.

[0007] Details of one or more embodiments of the subject matter described herein are given in the accompanying drawings and the description below. Other potential features, aspects, and advantages of the subject matter will be evident from the description, drawings, and claims. This specification also provides, for example, the following items: (Item 1) A device for controlling an array of light-emitting diodes (LEDs), wherein the device is An LED driver circuit configured to generate current, One or more LEDs of the LED array, wherein the one or more LEDs are electrically connected to the LED driver circuit, An electronic switching circuit electrically connected to one or more LEDs, wherein the electronic switching circuit is It is installed in one of several switching configurations. A portion of the current is directed away from the one or more LEDs such that the remainder of the current drives one or more LEDs, and a portion of the current corresponds to one of the plurality of switching configurations. An electronic switching circuit and A device equipped with the following features. (Item 2) The apparatus according to item 1, wherein each of the one or more LEDs has a first brightness in response to being driven by the current, and each of the one or more LEDs has a second brightness in response to being driven by the remainder of the current, the second brightness being less than the first brightness. (Item 3) The apparatus according to item 1, wherein the brightness of each of the one or more LEDs varies according to each of the multiple switching configurations. (Item 4) The above electronic switching circuit is One or more electronic switches configured to be installed in one of the plurality of switching configurations, One or more resistors, the one or more resistors being electrically connected to the one or more electronic switches, and configured to direct a portion of the current from the one or more resistors to the ports of the LED driver circuit, such that a portion of the current from the one or more resistors and the remaining portion of the current driving the one or more LEDs are combined at the ports of the LED driver circuit. The apparatus described in item 1, comprising: (Item 5) The above electronic switching circuit is Multiple electronic switches electrically connected in the first parallel configuration, A plurality of resistors electrically connected in a second parallel configuration, wherein each electronic switch of the plurality of electronic switches is electrically connected to one or more corresponding resistors of the plurality of resistors. The apparatus described in item 1, comprising: (Item 6) The aforementioned electronic switching circuit comprises N electronic switches, and the plurality of switching configurations are 2 N The apparatus described in item 1, comprising a switching configuration, wherein N is greater than or equal to 1. (Item 7) The apparatus according to item 1, wherein the electronic switching circuit comprises one or more variable resistors. (Item 8) The above electronic switching circuit is One or more electronic switches, One or more resistors, the one or more LEDs being electrically connected to each other in a series configuration, and each electronic switch of the one or more electronic switches being electrically connected to the corresponding LED of the one or more LEDs and the corresponding resistor of the one or more resistors, and The apparatus described in item 1, comprising: (Item 9) The apparatus as described in item 1, wherein the current is within the range of 20mA to 400mA, and the remaining portion of the current is within the range of 0mA to 380mA. (Item 10) The apparatus according to item 1, wherein the one or more LEDs comprises a first LED having a first color and a second LED having a second color, wherein the first color is different from the second color. (Item 11) A device for controlling an array of light-emitting diodes (LEDs), wherein the device is One or more LEDs in the aforementioned LED array, A first programmable LED driver circuit electrically connected to one or more of the aforementioned LEDs, wherein the first programmable LED driver circuit is It is installed in one of the first multiple configurations, A first current is generated that corresponds to one of the above-mentioned first multiple configurations. A first programmable LED driver circuit is configured as follows: A second programmable LED driver circuit electrically connected to one or more of the aforementioned LEDs, wherein the second programmable LED driver circuit is It is installed in the second of the second set of configurations, The first and second currents are combined to form a third current, which generates a second current corresponding to the second of the second plurality of configurations, in order to drive one or more LEDs. A second programmable LED driver circuit is configured as follows: A device equipped with the following features. (Item 12) The system further comprises a controller circuit electrically connected to the first programmable LED driver circuit and the second programmable LED driver circuit, wherein the controller circuit The first programmable LED driver circuit is installed in one of the first multiple configurations, and the first current is adjusted. installing the second programmable LED driver circuit in a second one of the second plurality of configurations, and adjusting the second current The apparatus according to item 11, configured to perform: (Item 13) Each of the one or more LEDs has a first minimum brightness in response to being driven by the first current, each of the one or more LEDs has a second minimum brightness in response to being driven by the second current, each of the one or more LEDs has a third minimum brightness in response to being driven by the third current, and the third minimum brightness is equal to the lower of the first minimum brightness and the second minimum brightness. The apparatus according to item 11. (Item 14) Each of the one or more LEDs has a first maximum brightness in response to being driven by the first current, each of the one or more LEDs has a second maximum brightness in response to being driven by the second current, each of the one or more LEDs has a third maximum brightness in response to being driven by the third current, and the third maximum brightness is equal to the higher of the first maximum brightness and the second maximum brightness. The apparatus according to item 11. (Item 15) The brightness of each of the one or more LEDs varies according to each configuration of the first plurality of configurations, and the brightness of each of the one or more LEDs varies according to each configuration of the second plurality of configurations. The apparatus according to item 11. (Item 16) The one or more LEDs comprise a first LED having a first color and a second LED having a second color, and the first color is different from the second color. The apparatus according to item 11. (Item 17) A method for controlling a light emitting diode (LED) array, the method comprising: generating a current by an LED driver circuit; By using one or more electronic switches, an electronic switching circuit is installed in one of several switching configurations, The electronic switching circuit directs a portion of the current away from one or more LEDs in the LED array such that the remaining portion of the current drives one or more LEDs, wherein the portion of the current corresponds to one of the plurality of switching configurations. Methods that include... (Item 18) The method according to item 17, wherein each of the one or more LEDs has a first brightness in response to being driven by the current, and each of the one or more LEDs has a second brightness in response to being driven by the remainder of the current, the second brightness being less than the first brightness. (Item 19) The method according to item 17, wherein the brightness of each of the one or more LEDs varies according to each of the multiple switching configurations. (Item 20) One or more resistors are used to direct a portion of the current to the port of the LED driver circuit, The electrical network combines a portion of the current from one or more resistors with the remaining portion of the current driving one or more LEDs at the ports of the LED driver circuit. The method described in item 17, further including the method described in item 17. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 illustrates a device for controlling an array of light-emitting diodes (LEDs).

[0009] [Figure 2] Figure 2 illustrates a device for controlling an LED array.

[0010] [Figure 3]Figure 3 illustrates a device for controlling an LED array.

[0011] [Figure 4] Figure 4 illustrates a device for controlling an LED array.

[0012] [Figure 5] Figure 5 illustrates a device for controlling an LED array.

[0013] [Figure 6] Figure 6 is a flowchart illustrating the operation of a method for controlling an LED array.

[0014] [Figure 7] Figure 7 is a flowchart illustrating the operation of a method for controlling an LED array. [Modes for carrying out the invention]

[0015] Detailed explanation Figure 1 illustrates a device for controlling a light-emitting diode (LED) array. LED arrays can be used in electronic displays, such as within devices (e.g., headsets) that provide virtual reality, augmented reality, or mixed reality experiences. LED arrays can also be used to provide illumination in aerospace lighting systems, automotive headlamps, traffic signals, cameras, medical devices, and / or other suitable systems. The device illustrated in Figure 1 includes a controller circuit 100, an LED driver circuit 108, one or more LEDs 112 of the LED array, and an electronic switching circuit 128. The LED driver circuit 108 is configured to generate a current 116 and power one or more LEDs 112. In some embodiments, the current 116 generated by the LED driver circuit 108 is in the range of 20mA to 400mA. The amount of current 116 will depend on the type of LED driver circuit 108 used. One or more LEDs 112 are electrically connected to the LED driver circuit 108 and powered by the LED driver circuit 108.

[0016] The electronic switching circuit 128 includes an electronic switch 120 and a resistor 124. The electronic switching circuit 128 is electrically connected to one or more LEDs 112. The electronic switching circuit 128 is configured to be installed in one of a plurality of switching configurations. For example, when the electronic switch 120 is opened, the electronic switching circuit 128 is installed in a first switching configuration, and current 116 flows through one or more LEDs 112, driving one or more LEDs 112 at a time. Each LED of one or more LEDs 112 is connected to a separate pull-down circuit in the LED driver circuit 108. In some embodiments, the controller circuit 100 is configured to generate a control signal 104 that activates only one of the one or more pull-down circuits at a time. Thus, only one of the one or more pull-down circuits is active at a time. Thus, only one of the one or more LEDs 112 is driven at a time.

[0017] When the electronic switch 120 is closed, the electronic switching circuit 128 is set to a second switching configuration. In the second switching configuration, the electronic switching circuit 128 is configured to direct a portion 132 of the current 116 away from one or more LEDs 112 through the resistor 124. The remaining portion 136 of the current 116 drives one or more LEDs 112. The portion 132 of the current 116 corresponds to the switching configuration in which the electronic switching circuit 128 is set. For example, in the first switching configuration, the portion 132 is zero. In the second switching configuration, when the electronic switch 120 is closed, the portion 132 corresponds to the voltage drop across the electronic switching circuit 128, which is divided by the resistance of the resistor 124. In some embodiments, the remaining portion 136 of the current 116 is in the range of 0mA to 380mA. Therefore, the brightness of each LED 112 is reduced when it is driven by the remaining portion 136 instead of the current 116.

[0018] In the device illustrated in Figure 1, each LED of one or more LEDs 112 has a first brightness in response to being driven by the current 116. When the electronic switching circuit 128 is not used, the minimum brightness limit of the LED array corresponds to the minimum limit with respect to the current 116 generated by the LED driver circuit 108. Each LED of one or more LEDs 112 has a second brightness in response to being driven by the remaining portion 136 of the current 116. When the electronic switching circuit 128 is used, the minimum brightness limit of the LED array corresponds to the minimum limit with respect to the remaining portion 136 of the current 116. The remaining portion 136 of the current 116 is less than the current 116. Therefore, the second brightness is less than the first brightness. Thus, when the electronic switching circuit 128 is used, the minimum brightness limit of the LED array is reduced compared to when the electronic switching circuit 128 is not used.

[0019] Figure 2 illustrates a device for controlling an LED array. The device illustrated in Figure 2 includes an LED driver circuit 200, one or more LEDs 204 of the LED array, and an electronic switching circuit 256. The LED driver circuit 200 is configured to generate a current 208 and power one or more LEDs 204. One or more LEDs 204 are electrically connected to the LED driver circuit 200 and powered by the LED driver circuit 200.

[0020] The electronic switching circuit 256 is electrically connected to one or more LEDs 204. In some embodiments, the electronic switching circuit 256 includes a plurality of electronic switches (216, 220, 224, ..., 228) electrically connected in a first parallel configuration. The electronic switching circuit 256 further includes a plurality of resistors (240, 244, 248, ..., 252) electrically connected in a second parallel configuration. Each electronic switch, for example, electronic switch 216, is electrically connected to one or more corresponding resistors, for example, resistor 240.

[0021] Multiple electronic switches are configured to install the electronic switching circuit 256 in one of multiple switching configurations. The electronic switching circuit 256 is configured to be installed in a specific switching configuration by closing different combinations of the multiple electronic switches. In each switching configuration, the electronic switching circuit 256 directs a portion 212 of the current 208 away from one or more LEDs 204 so that the remaining portion 260 of the current 208 drives one or more LEDs 204. The portion 212 of the current 208 corresponds to the switching configuration in which the electronic switching circuit 256 is installed.

[0022] The resistors (240, 244, 248, ..., 252) are electrically connected to a number of electronic switches (216, 220, 224, ..., 228) and configured to direct a portion of the current 212 to port 236 of the LED driver circuit 200. A portion of the current 208 flowing through one or more of the resistors (240, 244, 248, ..., 252), 212, and the remaining portion 260 of the current 208, which drives one or more LEDs 204, are combined with the current 232 and directed to port 236 of the LED driver circuit 200.

[0023] In some embodiments, the electronic switching circuit 256 includes N electronic switches, where N is greater than or equal to 1. For example, N can be 1, 17, 124, etc. The electronic switching circuit 256 thus closes different combinations of electronic switches, 2 N It can be installed in one of the following switching configurations at once. For example, consider an embodiment in which N is 4. In the first switching configuration, all four electronic switches (216, 220, 224, 228) are open, and a portion of the current 208, 212, is zero. In the second switching configuration, electronic switch 216 is closed, and the remaining three electronic switches (220, 224, 228) are open. In the third switching configuration, electronic switches 216 and 220 are closed, and electronic switches 224 and 228 are open. In the sixteenth switching configuration, all four electronic switches (216, 220, 224, 228) are closed.

[0024] A portion 212 of the current 208 varies according to the switching configuration in which the electronic switching circuit 256 is installed. For example, a portion 212 of the current 208 varies according to the resistance of the electronic switching circuit 256. Therefore, the remaining portion 260 of the current 208 varies according to the switching configuration in which the electronic switching circuit 256 is installed. The brightness of each LED 204, one or more, varies according to the remaining portion 260 of the current 208, so the brightness of each LED varies according to the switching configuration in which the electronic switching circuit 256 is installed. The brightness of the LED array is varied by closing different combinations of electronic switches (216, 220, 224, 228).

[0025] In some embodiments, the electronic switching circuit 256 includes one or more variable resistors. For example, one or more of the resistors (240, 244, 248, ..., 252) may be variable resistors. The resistance of each variable resistor can be adjusted by a controller circuit, such as the controller circuit 100 shown in Figure 1. Thus, a portion of the current 208 212 can be adjusted by adjusting the resistance in each variable resistor.

[0026] Figure 3 illustrates a device for controlling an LED array. The device illustrated in Figure 3 includes an LED driver circuit 300, one or more LEDs 312 of the LED array, and an electronic switching circuit 316. The LED driver circuit 300 is configured to generate current and power one or more LEDs 312. One or more LEDs 312 are electrically connected to the LED driver circuit 300 and powered by the LED driver circuit 300.

[0027] The electronic switching circuit 316 includes one or more electronic switches 304 and one or more resistors 308. One or more LEDs 312 are electrically connected to each other in a series configuration. Each electronic switch of one or more electronic switches 304 is electrically connected to the corresponding LED of one or more LEDs 312 and to the corresponding resistor of one or more resistors 308. When a particular electronic switch of one or more electronic switches 304 is closed, the electronic switching circuit 316 directs a portion of the current away from the corresponding LED, so that the remainder of the current drives the corresponding LED. Therefore, the brightness of the corresponding LED is reduced when a particular switch is opened compared to the brightness of the corresponding LED. Thus, the brightness of the LED array can be varied by closing different combinations of one or more electronic switches 304.

[0028] Figure 4 illustrates a device for controlling an LED array. The device illustrated in Figure 4 includes one or more LEDs 436 of an LED array, a first programmable LED driver circuit 412, a second programmable LED driver circuit 416, and a controller circuit 400. The first programmable LED driver circuit 412 is electrically connected to one or more LEDs 436 and configured to supply power to one or more LEDs 436. The first programmable LED driver circuit 412 is configured to be installed in one of a first set of configurations. In each of the first set of configurations, the first programmable LED driver circuit 412 generates a first current 420 to supply power to one or more LEDs 436. The first current 420 corresponds to the configuration in which the first programmable LED driver circuit 412 is installed. The controller circuit 400 is electrically connected to the first programmable LED driver circuit 412. The controller circuit 400 is configured to install the first programmable LED driver circuit 412 in each of the first set of configurations and to adjust the first current 420. For example, the controller circuit 400 generates a control signal 408 to install the first programmable LED driver circuit 412 in each configuration.

[0029] The second programmable LED driver circuit 416 is configured to be installed in a second of a set of second configurations. In each of the second set of configurations, the second programmable LED driver circuit 416 generates a second current 424 to power one or more LEDs 436. The second current 424 corresponds to the configuration in which the second programmable LED driver circuit 416 is installed. The controller circuit 400 is electrically connected to the second programmable LED driver circuit 416. The controller circuit 400 is configured to install the second programmable LED driver circuit 416 in each of the second set of configurations and to regulate the second current 424. For example, the controller circuit 400 generates a control signal 404 to install the second programmable LED driver circuit 416 in each configuration.

[0030] The brightness of each LED in one or more LEDs 436 varies according to a first current 420. The first current 420 varies according to each configuration in the first set of configurations. Therefore, the brightness of each LED in one or more LEDs 436 varies according to each configuration in which the first programmable LED driver circuit 412 is installed. The brightness of each LED in one or more LEDs 436 also varies according to a second current 424. The second current 424 varies according to each configuration in the second set of configurations. Therefore, the brightness of each LED in one or more LEDs 436 varies according to each configuration in which the second programmable LED driver circuit 416 is installed. The brightness of the LED array can be adjusted by using a controller circuit 400 to control the configurations in which the first programmable LED driver circuit 412 and the second programmable LED driver circuit 416 are installed.

[0031] The first current 420 and the second current 424 are combined with the third current 428 to drive one or more LEDs 436. For example, the first current 420 can be in the range of 1mA to 50mA. The second current 424 can be in the range of 50mA to 500mA. The third current 428 can be in the range of 1mA to 550mA. Each LED of one or more LEDs 426 has a first minimum brightness in response to being driven by the first current 420 (e.g., 1mA). Each LED of one or more LEDs 436 has a second minimum brightness in response to being driven by the second current 424 (e.g., 50mA). Each LED of one or more LEDs 436 has a third minimum brightness in response to being driven by the third current 428 (e.g., 1mA). The third minimum brightness is the lower of the first minimum brightness and the second minimum brightness.

[0032] Each of the one or more LEDs in the LED436 has a first maximum brightness in response to being driven by a first current 420 (e.g., 50 mA). Each of the one or more LEDs in the LED436 has a second maximum brightness in response to being driven by a second current 424 (e.g., 500 mA). Each of the one or more LEDs in the LED436 has a third maximum brightness in response to being driven by a third current 428 (e.g., 550 mA). The third maximum brightness is the higher of the first maximum brightness and the second maximum brightness.

[0033] One or more LEDs include a first LED having at least a first color (e.g., red) and a second LED having a second color (e.g., green). The first color is different from the second color. One or more blue LEDs can also be used to construct the LED array. In some embodiments, the controller circuit 400 programs at least one of the first programmable LED driver circuit 412 or the second programmable LED driver circuit 416 to adjust the brightness of each LED of one or more LEDs 436 within one frame cycle. The frame cycle corresponds to the cycle rate or image frame rate of the electronic display or lighting system using one or more LEDs 436. In other embodiments, the controller circuit 400 synchronizes the change in brightness of each LED of one or more LEDs 436 with the output of the electronic display or lighting system using one or more LEDs 436. For example, in a virtual reality game displayed on a virtual reality headset using one or more LEDs 436, the controller circuit 400 can synchronize the decrease in the brightness of the LEDs with the display of a specific image on the headset.

[0034] Figure 5 illustrates a device for controlling an LED array. The device illustrated in Figure 5 includes a controller circuit 500, an LED driver circuit 504, a red LED 508, a green LED 512, a blue LED 516, and an electronic switching circuit 520. The electronic switching circuit 520 includes an electronic switch 524 and three resistors 528, 532, and 536. In some embodiments, the device illustrated in Figure 5 is used to control a lighting system having an LED array with two or more unique colors, such as purple, amber, white, etc.

[0035] The LED driver circuit 504 is configured to generate a current 540 and supply power to LEDs 508, 512, and 516. The controller circuit 500 controls and operates the LED driver circuit 504 and adjusts the amount of current 540 generated. LEDs 508, 512, and 516 are electrically connected to and powered by the LED driver circuit 504. The electronic switching circuit 520 is electrically connected to LEDs 508, 512, and 516. The electronic switching circuit 520 is configured to be installed in one of two switching configurations. For example, when the electronic switch 524 is open, the electronic switching circuit 520 is installed in the first switching configuration. When the electronic switch 524 is closed, the electronic switching circuit 520 is installed in the second switching configuration.

[0036] The electronic switching circuit 520 directs a portion 544 of the current 540 away from LEDs 508, 512, and 516, so that the remaining portion 548 of the current 540 drives LEDs 508, 512, and 516, respectively. The portion 544 of the current 540 corresponds to the switching configuration in which the electronic switching circuit 520 is installed. For example, in the first configuration, the portion 544 of the current 540 is zero.

[0037] When the red LED 508 is driven in the second switching configuration, a portion 544 of the current 540 corresponds to the voltage drop across the red LED 508, divided by the resistance of resistor 528. When the green LED 512 is driven in the second switching configuration, a portion 544 of the current 540 corresponds to the voltage drop across the green LED 512, divided by the resistance of resistor 532. When the blue LED 516 is driven in the second switching configuration, a portion 544 of the current 540 corresponds to the voltage drop across the blue LED 516, divided by the resistance of resistor 536. The remaining portion 548 of the current 540 that drives LEDs 508, 512, and 516 is therefore always less than current 540 when the electronic switch is closed. For example, when the current 540 generated by the LED driver circuit 504 is in the range of 20mA to 400mA, the remaining portion 548 of the current 540 is in the range of 0mA to 380mA. The minimum brightness of LEDs 508, 512, and 516 in the second configuration (when the electronic switching circuit 520 is used) is therefore less than the minimum brightness of LEDs 508, 512, and 516 when the electronic switching circuit 520 is not used. The apparatus illustrated in Figure 5 therefore provides a lower minimum brightness, a wider dynamic brightness range, and improved sensitivity control for the LED array compared to conventional methods.

[0038] In some embodiments, using the apparatus illustrated in Figures 1-5, the brightness and color characteristics of an electronic display (or other lighting system) can be adjusted by characterizing the temperature and current dependence of each LED and, based on the characterization, adjusting the manner in which the electronic display receives and handles the light emitted from the LEDs. These two steps are sometimes referred to as “thermal calibration” or “color calibration” of the electronic display. The characterization step may occur during or after processing, for example, while the electronic display is still in the factory, by positioning a photodetector (e.g., a spectrometer) at a distance from the eyepiece from which the user’s eye would receive light during use. The photodetector sequentially detects the light output of each LED through the electronic display while a controller (e.g., a feedforward controller) iterates through multiple temperatures and currents. The light output of the LEDs is analyzed to extract chromaticity and luminance data, which are used to characterize each LED. When the electronic display is actually being used by a user, the calibration step is performed by measuring the temperature and adjusting the LED current and color calculation algorithm based on characteristic data such that the measured temperature is inferred. Details of the calibration process and feedforward control are disclosed in U.S. Patent Application No. 16 / 530,599 (which is incorporated herein by reference in its entirety).

[0039] Figure 6 illustrates a method for controlling an LED array. In some embodiments, the process illustrated in Figure 6 is carried out by the apparatus illustrated in Figure 1. In other embodiments, the process illustrated in Figure 6 is carried out by other apparatus, such as the apparatus illustrated in Figures 2, 3, or 5.

[0040] An LED driver circuit (e.g., LED driver circuit 108) generates a current (e.g., current 116) (604). The LED driver circuit 108 and current 116 are illustrated and described in more detail with reference to Figure 1. Current 116 is for powering one or more LEDs in the LED array (e.g., one or more LEDs 112). One or more LEDs 112 are illustrated and described in more detail with reference to Figure 1.

[0041] One or more electronic switches (e.g., electronic switch 120) install an electronic switching circuit (e.g., electronic switching circuit 128) into one of a plurality of switching configurations (608). The electronic switch 120 and the electronic switching circuit 128 are illustrated and described in more detail with reference to Figure 1. The electronic switching circuit 128 includes a resistor 124. The electronic switching circuit 128 is electrically connected to one or more LEDs 112. When the electronic switch 120 is opened, the electronic switching circuit 128 is installed into a first switching configuration, and current 116 flows through one or more LEDs 112, powering them one at a time.

[0042] The electronic switching circuit 128 directs a portion of the current 116 (e.g., a portion 132) away from one or more LEDs 112 in the LED array (612). The remaining portion of the current 116 (e.g., the remaining portion 136) drives one or more LEDs 112. The portion 132 of the current 116 corresponds to the switching configuration in which 128 is installed. Each LED has a first brightness in response to being driven by the current 116. Thus, the minimum brightness limit of the LED array corresponds to the minimum limit with respect to the current 116 when the electronic switching circuit 128 is not in use. Each LED has a second brightness in response to being driven by the remaining portion 136 of the current 116. Thus, the minimum brightness limit of the LED array corresponds to the minimum limit with respect to the remaining portion 136 of the current 116 when the electronic switching circuit 128 is in use. Therefore, the second brightness is less than the first brightness, and the minimum brightness limit of the LED array can be reduced when the electronic switching circuit 128 is used compared to when the electronic switching circuit 128 is not used.

[0043] Figure 7 illustrates a method for controlling an LED array. In some embodiments, the process illustrated in Figure 7 is carried out by the apparatus illustrated in Figure 4.

[0044] A controller circuit (e.g., controller circuit 400) installs a first programmable LED driver circuit (e.g., first programmable LED driver circuit 412) into one of the first set of configurations (704). The controller circuit 400 and the first programmable LED driver circuit 412 are illustrated and described in more detail with reference to Figure 4. For example, the controller circuit 400 generates a control signal 408 which installs the first programmable LED driver circuit 412 into each of the first set of configurations. The first programmable LED driver circuit 412 is electrically connected to one or more LEDs (e.g., one or more LEDs 436) and configured to power one or more LEDs 436. One or more LEDs 436 are illustrated and described in more detail with reference to Figure 4.

[0045] In each of the first set of configurations, the first programmable LED driver circuit 412 generates a first current 420 (708) to power one or more LEDs 436. The first current 420 corresponds to the configuration in which the first programmable LED driver circuit 412 is installed. The first current 420 is illustrated and described in more detail with reference to Figure 4.

[0046] The controller circuit 400 installs a second programmable LED driver circuit (e.g., a second programmable LED driver circuit 416) into the second of the second set of configurations (712). The second programmable LED driver circuit 416 is illustrated and described in more detail with reference to Figure 4. For example, the controller circuit 400 generates a control signal 404 to install the second programmable LED driver circuit 416 into each of the second set of configurations. The second programmable LED driver circuit 416 is configured to be electrically connected to one or more LEDs 436 and to supply power to one or more LEDs 436.

[0047] In each of the second set of configurations, the second programmable LED driver circuit 416 generates a second current 424 (716) to power one or more LEDs 436. The second current 424 corresponds to the configuration in which the second programmable LED driver circuit 416 is installed.

[0048] An electrical network (e.g., electrical network 432) combines a first current 420 and a second current 424 with a third current 428 (720) to drive one or more LEDs 436 of the LED array. The brightness of each LED varies according to the first current 420 and each configuration in which the first programmable LED driver circuit 412 is installed. The brightness of each LED also varies according to the second current 424 and each configuration in which the second programmable LED driver circuit 416 is installed. By controlling the configurations in which the first programmable LED driver circuit 412 and the second programmable LED driver circuit 416 are installed, the controller circuit 400 adjusts the brightness of the LED array.

[0049] In some configurations, the controller circuit installs a first programmable LED driver circuit into one of the first set of configurations. The first programmable LED driver circuit generates a first current corresponding to one of the first set of configurations. The controller circuit installs a second programmable LED driver circuit into a second of the second set of configurations. The second programmable LED driver circuit generates a second current corresponding to the second of the second set of configurations. The electrical network combines the first and second currents into a third current to drive one or more LEDs in the LED array.

[0050] In some configurations, installing a first programmable LED driver circuit in one of the first set of configurations regulates the first current. Installing a second programmable LED driver circuit in the second of the second set of configurations regulates the second current.

[0051] In some configurations, each of the one or more LEDs has a first minimum brightness in response to being driven by a first current. Each of the one or more LEDs has a second minimum brightness in response to being driven by a second current. Each of the one or more LEDs has a third minimum brightness in response to being driven by a third current. The third minimum brightness is equal to the lower of the first minimum brightness and the second minimum brightness.

[0052] In some configurations, each LED in one or more LEDs has a first maximum brightness in response to being driven by a first current. Each LED in one or more LEDs has a second maximum brightness in response to being driven by a second current. Each LED in one or more LEDs has a third maximum brightness in response to being driven by a third current. The third maximum brightness is equal to the higher of the first maximum brightness and the second maximum brightness.

[0053] In some configurations, the brightness of each LED, one or more LEDs, varies according to each configuration in the first set of configurations. The brightness of each LED, one or more LEDs, varies according to each configuration in the second set of configurations.

[0054] In some configurations, one or more LEDs include a first LED having a first color and a second LED having a second color. The first color is different from the second color.

[0055] In some configurations, the controller circuit adjusts the brightness of each LED in one or more LEDs of the LED array within a single frame cycle of the LED array.

[0056] In some configurations, the controller circuit synchronizes the output of the LED array with the brightness changes of each LED in one or more LEDs of the LED array.

Claims

[Claim 1] Dynamic control of the brightness of an LED array, etc.

Images