Temperature-compensated pixel drivers

Abstract

In a general aspect, a display includes a pixel including a red light emitter, a blue light emitter and a green light emitter. The display also includes respective current sources coupled with the red light emitter, the green light emitter, and the blue light emitter. The display further includes a temperature compensator configured to, based on an operating temperature of the display, determine respective current correction values for the red light emitter, the green light emitter, and the blue light emitter. The display also further includes a plurality of bias generators configured to, based on the respective current correction values, provide respective bias voltages to the respective current sources.

Description

TEMPERATURE-COMPENSATED PIXEL DRIVERSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 594.809, filed on October 31. 2023, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] Displays, such as display panels, can include a plurality of light emitting devices, such as light emitting diodes (LEDs). microLEDs (pLEDs), as well as associated circuitry for electrically driving such LEDs and / or pLEDs to emit light, e.g., red light, green light, or blue light to display images. In previous implementations, undesired variations in brightness and / or color of emited light can occur.SUMMARY

[0003] In a general aspect, a display includes a pixel including a red light emitter, a blue light emiter and a green light emiter. The display also includes respective current sources coupled with the red light emiter, the green light emiter, and the blue light emiter. The display further includes a temperature compensator configured to, based on an operating temperature of the display, determine respective current correction values for the red light emiter, the green light emiter, and the blue light emiter. The display also further includes a plurality of bias generators configured to, based on the respective current correction values, provide respective bias voltages to the respective current sources.

[0004] In another general aspect, a method for operating a display includes determining an operating temperature of the display. The method further includes determining, based on the operating temperature, a correction value for a drive current for driving a light emitter included in the display. The method also includes providing the correction value to a bias generator, and providing, by the bias generator based on the correction value, a bias to a current source. The method also further includes providing, based on the bias, the drive current to the light emiter.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a block diagram schematically illustrating an example display including temperature-compensated pixel drivers.

[0006] FIG. 2 is a block and circuit diagram schematically illustrating an example of temperature compensation for a light emitter of a pixel group.

[0007] FIG. 3 is a flowchart illustrating an example method of operation for the pixel group of FIG. 2.

[0008] FIG. 4 is a block diagram illustrating an example display system that can be implemented using temperature-compensated pixel drivers, such as in the examples of FIGs. I and 2.

[0009] FIG. 5 is a block diagram illustrating an example controller that can be included in the display system of FIG. 4.

[0010] In the drawings, which are not necessarily draw n to scale, like reference labels may indicate like and / or similar components (elements, structures, etc.) in different views. The drawings illustrate generally, by way of example, but not by way of limitation, various implementations discussed in the present disclosure. Reference labels shown in one drawing may not be repeated for the same, and / or similar elements in related views. Reference labels that are repeated in multiple drawings may not be specifically discussed with respect to each of those drawings, but are provided for context between related views. Also, not all like elements in the drawings may be specifically referenced with a reference label when multiple instances of that element are illustrated.DETAILED DESCRIPTION

[0011] This disclosure is directed to light emitting devices, such as light emitting diodes (LEDs), microLEDs (pLEDs), and displays (display panels) including such light emitting devices. This disclosure is further directed to circuitry for electrically driving such LEDs and / or pLEDs to emit light, e.g., red light, green light, and / or blue light, such as in a pixel group (pixel circuit, pixel, display pixel, etc.) of a display panel. In this disclosure light emitting devices may be collectively referred to as pLEDs for purposes of discussion and illustration.

[0012] Displays can include a plurality of pixel groups. For instance, in some implementations, an emissive display (a display panel, etc.) can include hundreds of thousands, to millions of pixel groups. Each pixel group can include a plurality of light emitters, such as a plurality of pLEDs, e.g., a red pLED, a green pLED, and a blue pLED. Each pLED (or other type of light emitter) of a corresponding pixel group can be driven by a current source that operates in accordance with a respective bias voltage (Vbias), such as a V bias per pLED color.

[0013] One technical problem with previous display panels is that changes in operating temperature affect operation performance of a display. Such changes in operating temperature can occur as a result of changes in ambient temperature in which a display is operating, and / or due to thermal energy generated during operation of the display, as some examples. For instance, changes in operating temperature change the quantum efficiency of the pLED. That is, brightness of light emitted, and / or wavelength (color) of light emitted can be affected by changes in operating temperature. That is, respective brightnesses of emitted light and / or respective wavelengths of emitted light for pLEDs included in pixels of a display can vary across operating temperature. Such variations (quantum efficiency changes) may not be uniform for different color pLEDs. That is. rates of quantum efficiency (QE) change as a function of temperature vary for different colors of pLEDs. For example, operating performance of red pLEDs (red light emitters) can have larger QE variation (higher temperature dependence), and / or different rates of QE change over temperature than operating performance for green pLEDs (green light emiters) and / or blue pLEDs (blue light emiters). Similarly, operating performance (e.g., QE) for green pLEDs can vary at a different rate across temperature than operating performance (e.g., QE) for blue pLEDs.

[0014] A technical solution to the foregoing technical problem is implementing displays that compensate, e.g., on a per pLED color basis, for such changes. A technical benefit of this technical solution is to reduce or eliminate variations in brightness and / or variations in wavelengths of light emitted by pLEDs of pixel groups of a display. For instance, the approaches described herein can facilitate implementing temperature compensated pixel driver circuits that adjust respective currents used to drive pLEDs included in pixels of a display based on a measured operating temperature of the display. In some implementations, drive current adjustments for each pLED color (e.g., red. green, and blue) can be made independently of one another. A technical benefit of the foregoing is a reduction of variation in operation (e.g., brightness and / or wavelength or emited light).

[0015] In some implementations, the approaches described herein can be used to implement a multi-color, binary -modulated, micro-emiter (pLED) display, such as a pLED display panel, including a plurality of pLEDs arranged in pixel groups. For instance, as described herein, a pixel group (or pixel) can include pLEDs of different colors, e.g., a red pLED, a green pLED, and a blue pLED, which can be used to provide light in a range of colors in the visible spectrum and / or to produce grayscale images.

[0016] FIG. 1 is a block diagram that schematically illustrates an example display 100 that implements temperature drive compensation for light emiters (pLEDs) of the display100. That is, the display 100 can be referred to as including temperature-compensated pixel drivers. For instance, the display 100 can adjust drive currents for pLEDs of corresponding pixel groups to compensate for variations in operating temperature. That is, the display 100 can independently compensate for temperature-dependent operation performance variations for each pLED color of pixels of the display 100, which can reduce variation in operation (such as display quality’, brightness, color consistency, etc.) of the display 100 over a range of operating temperatures. For instance, as operating temperature of the display 100 increases, drive current for each pLED color can be independently increased to compensate for reduced QE. Likewise, as operating temperature of the display 100 decreases, drive currents for each pLED color can be independently decreased to compensate for increased QE. Such compensation (e.g., changes in drive current) can be based on characterization and / or simulation data for each color of pLED used in a corresponding display.

[0017] As shown in FIG. 1, the display 100 includes a temperature compensator block 105, which can be configured to determine per color drive current adjustments for respective pixel driver currents for pLEDs of the display 100, which can reduce variation in operating performance of the display 100 over temperature. For instance, the temperature compensator block 105 can provide, based on an operating temperature of the display 100, a plurality of drive current correction values (e.g., a correction value per pLED color). In some implementations, the drive current correction values 145 can be relative to respective reference drive currents for each pLED colors, e.g.. nominal drive currents for each pLED color at a nominal operating temperature. Depending on an operating temperature of the display 100, e.g., as determined by the temperature compensator block 105, the drive current correction values 145 can indicate that respective increases in drive current from the corresponding reference currents are desired (e.g.. operating temperature is greater than a nominal temperature), or that decreases in the respective drive currents from the corresponding reference currents are desired (e.g., operating temperature is below the nominal temperature). In some implementations, if pLED drive current at the respective reference current for a given pLED color is desired (e.g., operating temperature is at the nominal temperature), a corresponding drive current correction value of zero (e.g.. zero change from the reference current) can be provided by the temperature compensator block 105.

[0018] In some implementations, a single drive current correction value can be provided by the temperature compensator block 105, and respective adjustments to drive current for each pLED color can be made based on that single correction value. The specificapproach for providing separate, per pLED color drive current correction values, or a single drive current correction value, will depend on the particular implementation.

[0019] In this example, the display 100 also includes programmable pixel bias generators 150 (bias regulators, bias circuits, etc.), which can receive the drive current correction values 145 from the temperature compensator block 105. The programmable pixel bias generators 150, based on the provided drive correction values 145. can respectively provide Vbias voltages 160 (e.g., a bias voltage per pLED color) to respective pixel drive current sources for each color of pLED of pixels in a pixel array 170. In this example, current sampling values 180, e.g., one for each pLED color, can be provided as feedback from the pixel array 170 to the programmable pixel bias generators 150 for further adjustment (e.g., fine tuning) of the provided Vbias voltages 160. That is, pixel drive currents can be further adjusted using a feedback loop based on current samples provided from the pixel array 170 to the programmable pixel bias generators 150. Accordingly, as changes to the Vbias voltages 160 occur in response to changes in the drive current correction values 145, respective drive currents provided to the pLEDs of the pixel array 170 (e.g.. per pLED color) by their corresponding current sources will be adjusted to compensate for changes in operating temperature, and current sampling feedback can be used to further adjust those drive currents.

[0020] In some implementations, the programmable pixel bias generators 150 and respective current sources of the pixel array 170 can operate as respective current mirrors. For instance, with reference to one the programmable pixel bias generators 150, the bias generator can include a variable resistance circuit (e.g. a resistor ladder or resistor matrix) that produces a reference current that is mirrored by its corresponding current source in the pixel array using a voltage bias corresponding with the reference current that is produced by the bias generator. The variable resistance can be controlled by a corresponding drive current correction value of the drive current correction values 145. That is, the drive cunent correction value can be used to establish the reference current. A respective current sampling value of the current sampling values 180 can be provided to the bias generator, e.g., as a voltage across a current sense resistor. In this example, that current sampling value and the bias voltage produced by the generator can be provided as inputs to a sense amp. e.g., to tune the bias voltage so that the mirrored current through the current source in the pixel array matches, or converges with, the reference current in the bias generator. In other implementations, other approaches can be used to generate bias voltages and pLED drive currents.

[0021] As show n in FIG. 1, in this example, image source data 190 can be provided to a display processor 195. Based on the image source data 190. the display processor 195 can control operation of the pixel array 170 to display images corresponding with the image source data 190, w here currents supplied to pLEDs of the pixel array 170 for displaying such images are determined based on the Vbias voltages 160 provided by the programmable pixel bias generators 150, where those Vbias voltages 160 are determined by (established by, based on. etc.) the drive current correction values 145 provided by the temperature compensator block 105.

[0022] In the display 100 of FIG. 1, by w ay of example, the temperature compensator block 105 includes a temperature sensor 110, an analog-to-digital converter (analog-to-digital converter 120). an LED drive current correction module 130, and a digital -to-analog converter (D-A converter 140). In this example, the temperature sensor 1 10 can be a thermistor, a thermocouple, or other temperature sensing devices that is included in the display 100. In some implementations, a plurality of temperature sensors 110 can be used, and a value, such as a voltage, indicating an average operating temperature can be provided to the analog-to-digital converter 120 by the plurality of temperature sensors 110. In some implementations, multiple temperature compensator blocks 105, such as for corresponding regions of a display can be included (e.g., a temperature compensator block 105 for each quadrant of the display 100). Such implementations can help further reduce variation in display performance, such as when operating temperature varies across a display.

[0023] In the example of FIG. 1 , the analog-to-digital converter 120 can then convert the value (or voltage) provided by the temperature sensor(s) 110 to a digital value indicating the operating temperature of the display 100. That digital value can then be used to determine one or more LED drive current correction values, such as a correction value per color, based on the operating temperature. For instance, the LED drive current correction values could be determined using a number of different approaches, such as indexing a lookup table using the digital value, calculating a per pLED color temperature transfer function, e.g., a polynomial approximation, using the digital value, among other possible approaches. As described herein, such lookup tables and / or transfer functions can be based on respective characterization and / or simulation data for each pLED color, where such characterization data is multi-variable, e.g., temperature, drive current and brightness (QE) for each pLED color.

[0024] The LED drive correction value or values determined by the LED drive current correction module 130, in this example implementation, are digital values that arethen provided to the D-A converter 140. The D-A converter 140 can then convert the received digital values from the LED drive current correction module 130 to corresponding analog values, which are then communicated, as the drive current correction values 145, to the programmable pixel bias generators 150 as analog values. The programmable pixel bias generators 150 then respectively generate bias voltages 160 (per pLED color) based on the drive current correction values 145.

[0025] In some implementations, the temperature compensator block 105 can be fully digital, where the temperature sensor 110 provides a digital value representing operating temperature to the LED drive current correction module 130, and the drive current correction values 145 provided to the programmable pixel bias generators 150 are digital values. In such implementations, the analog-to-digital converter 120 and the D-A converter 140 can be omitted. In other implementations, the temperature compensator block 105 can be fully analog. In such approaches, the drive current correction values 145 can be based on analog signal processing an indicated temperature provided by the temperature sensor 110. Again, in such implementations, the analog-to-digital converter 120 and the D-A converter 140 can be omitted.

[0026] FIG. 2 is a block and circuit diagram (circuit 200) schematically illustrating an example of temperature compensation for a light emitter of a pixel group. The example of FIG. 2 illustrates, by way of example, temperature-compensated driving for single pLED, which can be similarly implemented for each pLED of pixels a display (or for pixels of a corresponding region of a display).

[0027] In the example of FIG. 2, the circuit 200 includes a temperature sensing block 205. In some implementations, the temperature sensing block 205 can be used for temperature-compensated pixel driving for pixels of an entire display, or for pixels of a corresponding region of the display. That is, the temperature sensing block 205 can be used (shared) to determine operating temperature for temperature-compensated driving of pLEDs (red, green and blue pLEDs) of a plurality of pixels, such as all pixels of a display or a region of a display. As shown in FIG. 2, the temperature sensing block 205 includes a temperature sensor 210 and an analog-to-digital converter 220, which can operate as discussed with respect to the temperature sensor 110 and the analog-to-digital converter 120 of FIG. 1.

[0028] The circuit 200 further includes a current correction block 230, which can determine a current correction value, e.g., a digital value, for a corresponding color of pLED being driven. For instance, the current correction block 230 can be implemented using a lookup table, a transfer function, or other mechanism for determining a current correctionvalue, such as was discussed with respect to the LED drive current correction module 130 of FIG. 1. The current correction value determined by the current correction block 230 can then be provided to a bias control circuit 240, which can include a D-A converter. The bias control circuit 240 can convert the drive current correction value provided by the current correction block 230 to an analog value 245, such as was discussed with respect to the D-A converter 140 of FIG. 1. The analog value (e.g., voltage) is produced by the bias control circuit 240 and provided to a bias circuit 250, which can then generate a corresponding bias voltage 260 that is provided to a current source 255 to provide a temperature-compensated drive current to a pLED 270 of the circuit 200, such as using the approach described above with respect to FIG. 1. As shown in FIG. 2, that drive current can be provided to the pLED 270 through a driver switch 285 that is controlled by a memory 275 (e.g. an SRAM cell), where data in the memory 275 corresponds to image data provided to a corresponding pixel circuit, e.g., by a display processor (e.g., the display processor 195 of FIG. 1 or the controller 500 of FIGs. 4 and 5. As further shown in FIG. 2, the drive current of the current source 255 can be sampled and provided to the bias circuit 250 as feedback signal 280, which be used to adjust the bias voltage provided to the current source 255. The feedback signal 280 can then be used, by bias circuit 250, to further adjust the drive current of the current source 255, such as using the approach described above with respect to FIG. 1.

[0029] FIG. 3 is a flowchart illustrating an example method 300 of operation for the pLED 270 of FIG. 2, where the method 300 can be independently performed for temperature- compensated driving pLEDs of pixels of a display, e g., a plurality of pixels, all pixels, or pixels in a given region of the display. The method 300 includes, at block 310, determining an operating temperature of the display. For instance, a digital value indicating the operating temperature can be generated by the temperature sensing block 205 of the circuit 200. At operation 320, the method 300 includes determining, based on the operating temperature, a correction value for a drive current for a light emitter of a specific color, such as the pLED 270. In an example implementation, the operation 320 can be performed by the current correction block 230 and the bias control circuit 240 of the circuit 200. At operation 330, the correction value of operation 320 is provided to a bias generator, such as the bias circuit 250. At operation 340, the bias generator provides a bias to a current source, such as the current source 255. The bias provided at operation 340 is based on the correction value of operation 320 and / or current sampling feedback from a corresponding current source, e.g. the current source 255, such as was described with respect to FIG. 2. At operation 350, the method 300 includes providing, based on the bias provided at operation 340, the drive current to thepLED, e.g., through a driver switch (285) controlled by a memory storing corresponding image data.

[0030] FIG. 4 is a schematic block diagram of an example display 400 that can be implemented using temperature compensated pixel drivers, such as those described herein. As shown in FIG. 4, the display 400 includes a plurality of pixels arranged in a 2D grid (i.e. , pixel array 420). For purposes of illustration and discussion of the display 400, each pixel 421 of the display 400 is illustrated by a single pLED and a corresponding SRAM. In some implementations, as noted above, each pixel 421 of the display 400 can be implemented using temperature compensated pixel drivers, such discussed respect the display 100 of FIG. 1 and or the temperature compensated pixel driver (circuit 200) of FIG. 2. That is, each pixel 421 can include a red pLED. a green pLED and a blue pLED with corresponding current sources that are driven by respective bias generators, where the bias generators operate based on drive current correction values and / or sampling of corresponding drive currents, such as described herein.

[0031] The SRAM can include a memory cell for setting and maintaining an illumination state of a corresponding pLED of a pixel group (e.g., as ON or OFF in correspondence with an image being displayed). The state of SRAMs of a pixel circuit (for each pLED included in a pixel group), can be controlled (e.g., set / reset) by a signal (e.g., bitline signal) transmitted over a column conductor (e.g., a bit-line) coupled to the SRAM. For instance, in the example of FIG. 4, the SRAM of each pixel 421 is coupled to a corresponding bit-line based on a signal (e.g., word-line signal) transmited over a row conductor (e.g., word-line) to the pixel 421. Accordingly, the display 400 further includes a word-line driver 412 configured to transmit a word-line signal to a word-line (e.g.. row) of the pixel array 420. The word-line signal can activate a row so that each pixel 421 in an active row is coupled to its respective bit-line.

[0032] As shown in FIG. 4, the display 400 further includes a bit-line driver 413 configured to transmit bit-line signals to the bit-lines of the pixels in an active row. The bitline signals may change or maintain the state of the SRAMs of pixels 421 in an active row according to a bit plane for an image being displayed. In some implementations, a bit-line signal is a differential signal. In this case, each bit-line may include a positive bit-line (BL+) configured to cany' a positive bit-line signal and a negative bit-line configured to cany7a negative bit-line signal (BL-). In such differential configurations, the positive bit-line and the negative bit-line may be referred to collectively as the bit-line.

[0033] The display 400 further includes a controller 500 configured to control the operation of the word-line driver 412 and the bit-line driver 413 to render a bit plane using the pixel array 420. For example, the controller 500 may transmit a word-line signal (i.e., ROW) to activate a row and then transmit the bit plane data (i.e., DATA(COLUMN)) to the columns of the activated row in parallel.

[0034] The controller 500 may be configured to address and write to the SRAMs of the pixel array 420 so that each micro-LEDs is illuminated (e.g., ON) or not illuminated (e.g., OFF) according to a bit plane. Each bit plane may be rendered on the pixel array 420 on a row-by-row basis until every row necessary for rendering the bit plane has been activated.

[0035] In some implementations, a rendering process includes transmitting a wordline signal to activate a row. After being activated, a bit-line signal for each pixel in the row controls each pLED of a pixel group according to the bit plane data for each pixel in the active row. After the bit-line signals configure (e.g., write to) the pixels of the active row, the row may be deacti vated, and another row may be activated until all rows of a bit plane have been activated. The SRAMs for pixels in deactivated rows can hold the pixels of the deactivated rows ON or OFF while the other rows of the bit plane are activated. After writing a bit plane to the SRAM cells of the pixel array 420, the SRAMs can hold their values (e.g., 0, 1) until they are changed. As a result, updating the values (e.g., red, green and blue values) in an SRAM may only require a portion of the SRAM cells to change their state e.g., flip) from bit plane to bit plane. This feature of the display 400 can contribute to low power consumption of the display. A sequence of binary bit planes, in which each pLED of a pixel circuit is either ON (e.g., SRAM at binary 1) or OFF (e.g., SRAM at binary' 0) may be rendered at a high rate, so as to display a stable image perceived by an observer, without visual artifacts, such as flicker, etc.

[0036] FIG. 5 is a block diagram of an example controller 500 for a display, such as the display 400 of FIG. 4 (display system). As noted above, the display 400 can be implemented using temperature-compensated pixels drivers, as described herein. In some implementations, the controller 500 can be implemented as a unitary device, or can be implemented as part of a distributed computing system. In this example, the controller 500 includes digital processing, logic, and memory to perform operations associated with controlling the pixels (and the pLEDS of each pixel, e.g., sub-pixels) in a pixel array to render (e.g., display) an image. These operations may be performed by modules, which can include circuitry and / or software to perform one or more of the operations. In other words, the controller 500 may be configured by software instructions stored in (and recalled from) anon-transitory computer readable memory to perform the methods to control the pixels of the display.

[0037] As shown in FIG. 5, the controller 500 includes a display preprocessor module (i.e., display preprocessor 510). The display preprocessor 510 may be configured to receive an image for display. The image may be a grayscale image or a color image. A color image for display can include three color channels, each represented by a gray scale image. Accordingly, for purposes of illustration, an example of a grayscale image for display is discussed below. In this example, preprocessing performed by the display preprocessor 510 may include formatting and filtering (e.g., thresholding) necessary to adapt an image to the format and structures necessary for rendering in, for example, the display 400.

[0038] The controller 500 further includes a bit plane generator 515 configured to generate a set of bit planes based on the received image data. The generation by the bit plane generator 515 may result in a number of bit planes corresponding to a bit depth of a corresponding display. The bit planes can be written to a bit plane buffer 550 (e.g., memory), which can receive and store bit planes as they are generated.

[0039] Such bit planes may be stored until all bit planes in a bit plane sequence are complete and ready for rendering. In come implementations, compression (e.g., lossless compression) may be used to reduce a size (e.g., storage capacity ) of a bit plane buffer (not shown). Such a bit plane buffer may be partitioned into segments defined by the memory locations associated with the segment. The segments can be configured to store particular bit planes. For example, pairs of bit planes may be written to each segment of the bit plane buffer 550.

[0040] As shown in FIG. 5, the controller 500 may further include a bit plane reader 555 configured to recall nonzero bit planes from the bit plane buffer 550. In particular, the bit plane reader 555 may assemble the sequence of bit planes by recalling the bit planes from their respective segments in the bit plane buffer 550. In some implementations, the bit plane reader 555 may be further configured to decompress the recalled bit planes.

[0041] The controller 500 further includes a display post processor 560 that can create a weighted sequence of bit planes and the word-line and bit-line signals necessary for rendering the bit planes on a pixel array, such as the pixel array 420 of the display 400. For example, the display post processor 560 can include a sequence timing generator that is configured to control the timing of the bit periods of a rendering period. In other words, the display post processor 560 can generate PWM signals for the pixels of the display.

[0042] In a general aspect, a display includes a pixel including a red light emitter, a blue light emitter and a green light emitter. The display also includes respective current sources coupled with the red light emitter, the green light emitter, and the blue light emitter (e.g., a current source coupled with the red light emitter, a current source coupled with the green light emitter, and a current source coupled with the blue light emitter). The display- further includes a temperature compensator configured to, based on an operating temperature of the display-, determine respective current correction values for the red light emitter, the green light emitter, and the blue light emitter (e.g., a current correction value for the red light emitter, a current correction value for the green light emitter, and a current correction value for the blue light emitter). The display also further includes a plurality- of bias generators configured to, based on the respective current correction values, provide respective bias voltages to the respective current sources (e.g., a current correction value for the current source coupled with the red light emitter, a current correction value for the current source coupled with the green light emitter, and a current correction value for the current source coupled with the blue light emitter).

[0043] Implementations can include one or more of the following details or aspects, alone or in combination. For example, the respective current correction values can indicate respective adjustments to reference drive currents for the red light emitter, the green light emitter, and the blue light emitter.

[0044] The respective bias voltages can also be based on respective sampled currents of the respective current sources.

[0045] The temperature compensator can include a temperature sensor, an analog-to- digital converter coupled w ith the temperature sensor, a drive current correction determination block coupled with the analog-to-digital converter, and a digital-to-analog converter coupled with the drive current correction determination block. The digital-to- analog converter can be configured to communicate the respective current correction values to the plurality of bias generators.

[0046] The temperature compensator can include a temperature sensor, an analog-to- digital converter coupled with the at least one temperature sensor, a red drive current correction determination block coupled with the analog-to-digital converter, a green drive current correction determination block coupled w ith the analog-to-digital converter, a blue drive current correction determination block coupled with the analog-to-digital converter, a first digital-to-analog converter coupled with the red drive current correction determination block, a second digital-to-analog converter coupled with the green drive current correctiondetermination block, and a third digital-to-analog converter coupled with the blue drive current correction determination block.

[0047] The red drive current correction determination block can be configured to determine a first current correction value using a first lookup table, and provide the first current correction value to a first bias generator of the plurality of bias generators. The first bias generator can be coupled with the respective current source for the red light emitter.

[0048] The green drive current correction determination block can be configured to: determine a second current correction value using a second lookup table, and provide the second current correction value to a second bias generator of the plurality of bias generators. The second bias generator can be coupled with the respective current source for the green light emitter.

[0049] The blue drive current correction determination block can be configured to: determine a third current correction value using a third lookup table, and provide the third current correction value to a third bias generator of the plurality of bias generators. The third bias generator can be coupled with the respective current source for the green light emitter.

[0050] The red drive current correction determination block can be configured to determine a first current correction value using a first transfer function, and provide the first current correction value to a first bias generator of the plurality7of bias generators. The first bias generator can be coupled with the respective current source for the red light emitter.

[0051] The green drive current correction determination block can be configured to: determine a second current correction value using a second transfer function, and provide the second current correction value to a second bias generator of the plurality7of bias generators. The second bias generator can be coupled with the respective current source for the green light emitter.

[0052] The blue drive current correction determination block can be configured to determine a third current correction value using a third transfer function, and provide the third current correction value to a third bias generator of the plurality of bias generators. The third bias generator can be coupled with the respective current source for the green light emitter.

[0053] The display can include a first driver switch coupling a first current source of the respective current sources with the red light emitter. The display can include a second driver switch coupling a second current source of the respective current sources with the green light emitter. The display can include a third driver switch coupling a third current source of the respective current sources with the blue light emitter.

[0054] In another general aspect, a method for operating a display includes determining an operating temperature of the display. The method further includes determining, based on the operating temperature, a correction value for a drive current for driving a light emitter included in the display. The method also includes providing the correction value to a bias generator, and providing, by the bias generator based on the correction value, a bias to a current source. The method also further includes providing, based on the bias, the drive current to the light emitter.

[0055] Implementations can include one or more of the following details or aspects, alone or in combination. For example, the method can further include sampling the drive current and adjusting, based on the sampling, the drive current.

[0056] The correction value can indicate one of an increase in the drive current; or a decrease in the drive current.

[0057] Determining the operating temperature of the display can include generating an analog signal indicating the operating temperature of the display, and performing an analog to digital conversion of the analog signal to generate a digital temperature value.

[0058] Determining the correction value can include indexing a lookup table with the digital temperature value.

[0059] Determining the correction value can include calculating, based on the digital temperature value, a transfer function.

[0060] The light emitter can be one of a red light emitter, a green lighter emitter, or a blue light emitter of a pixel group of the display.

[0061] The correction value can be a first correction value, the drive current can be a first drive current, the light emitter can be a first light emitter, the bias generator can be a first bias generator, the bias can be a first bias, and the current source can be a first current source. The method can include determining, based on the operating temperature, a second correction value for a second drive current for driving a second light emitter included in the display, and providing the second correction value to a second bias generator. The method can include providing, by the second bias generator based on the second correction value, a second bias to a second current source, and providing, based on the second bias, the second drive current to the second light emitter. The method can include determining, based on the operating temperature, a third correction value for a third drive current for driving a third light emitter included in the display, and providing the third correction value to a third bias generator. The method can include providing, by the third bias generator based on the third correction value,a third bias to a third current source, and providing, based on the third bias, the third drive current to the third light emitter.

[0062] The first light emitter can be a red light emitter of a pixel of the display. The second light emitter can be a green light emitter of the pixel. The third light emitter can be a blue light emitter of the pixel.

[0063] Example implementations can include a non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform any of the methods described above. Example implementations can include an apparatus including means for performing any of the methods described above. Example implementations can include an apparatus including at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform any of the methods described above.

[0064] Various implementations of the systems and techniques described here can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0065] These computer programs (also known as programs, softw are, softw are applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and / or object-oriented programming language, and / or in assembly / machine language. As used herein, the terms “machine-readable medium” “computer-readable medium” refers to any computer program product, apparatus and / or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0066] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the specification.

[0067] In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.

[0068] While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is. therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the implementations. It should be understood that they have been presented by way of example only, not limitation, and various changes in form and details may be made. Any portion of the apparatus and / or methods described herein may be combined in any combination, except mutually exclusive combinations. The implementations described herein can include various combinations and / or sub-combinations of the functions, components and / or features of the different implementations described.

[0069] While example implementations may include various modifications and alternative forms, implementations thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example implementations to the particular forms disclosed, but on the contrary, example implementations are to cover all modifications, equivalents, and alternatives falling within the scope of the claims. Like numbers refer to like elements throughout the description of the figures.

[0070] Some of the above example implementations are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations as sequential processes, many of the operations may be performed in parallel, concurrently or simultaneously. In addition, the order of operations may be re-arranged. The processes may be terminated when their operations are completed, but may also have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, subprograms, etc.

[0071] Methods discussed above, some of which are illustrated by the flow charts, may be implemented by hardware, software, firmware, middleware, microcode, hardwaredescription languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine or computer readable medium such as a storage medium. A processor(s) may perform the necessary tasks.

[0072] Specific structural and functional details disclosed herein are merely representative for purposes of describing example implementations. Example implementations, however, be embodied in many alternate forms and should not be construed as limited to only the implementations set forth herein.

[0073] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example implementations. As used herein, the term and / or includes any and all combinations of one or more of the associated listed items.

[0074] The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of example implementations. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It ill be further understood that the terms comprises, comprising, includes and / or including, when used herein, specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0075] It should also be noted that in some alternative implementations, the functions / acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality / acts involved.

[0076] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example implementations belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0077] Lastly, it should also be noted that whilst the accompanying claims set out particular combinations of features described herein, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features or implementations herein disclosed irrespective of whether or not that particular combination has been specifically enumerated in the accompanying claims at this time.

Claims

WHAT IS CLAIMED IS:

1. A display comprising: a pixel including a red light emitter, a blue light emitter and a green light emitter; respective current sources coupled with the red light emitter, the green light emitter, and the blue light emitter; a temperature compensator configured to, based on an operating temperature of the display, determine respective current correction values for the red light emitter, the green light emitter, and the blue light emitter; and a plurality' of bias generators configured to, based on the respective current correction values, provide respective bias voltages to the respective current sources.

2. The display of claim 1, wherein the respective current correction values indicate respective adjustments to reference drive currents for the red light emitter, the green light emitter, and the blue light emitter.

3. The display of claim 1 or 2, wherein the respective bias voltages are further based on respective sampled currents of the respective current sources.

4. The display of any of claims 1 to 3, wherein the temperature compensator includes: a temperature sensor; an analog-to-digital converter coupled with the temperature sensor; a drive current correction determination block coupled with the analog-to-digital converter; and a digital-to-analog converter coupled with the drive current correction determination block.

5. The display of claim 4. wherein the digital-to-analog converter is configured to communicate the respective current correction values to the plurality of bias generators.

6. The display of any of claims 1 to 3, wherein the temperature compensator includes: a temperature sensor; an analog-to-digital converter coupled with the temperature sensor; a red drive current correction determination block coupled with the analog-to-digital converter; a green drive current correction determination block coupled with the analog-to- digital converter; a blue drive current correction determination block coupled with the analog-to-digital converter; a first digital-to-analog converter coupled with the red drive current correction determination block; a second digital-to-analog converter coupled with the green drive current correction determination block; and a third digital-to-analog converter coupled with the blue drive current correction determination block.

7. The display of claim 6, wherein: the red drive current correction determination block is configured to: determine a first current correction value using a first lookup table; and provide the first current correction value to a first bias generator of the plurality7of bias generators, the first bias generator being coupled with the respective current source for the red light emitter; the green drive current correction determination block is configured to: determine a second current correction value using a second lookup table; and provide the second current correction value to a second bias generator of the plurality7of bias generators, the second bias generator being coupled with the respective current source for the green light emitter; and the blue drive current correction determination block is configured to: determine a third current correction value using a third lookup table; and provide the third current correction value to a third bias generator of the plurality7of bias generators, the third bias generator being coupled with the respective current source for the green light emitter.

8. The display of claim 6, wherein: the red drive current correction determination block is configured to: determine a first current correction value using a first transfer function; and provide the first current correction value to a first bias generator of the plurality of bias generators, the first bias generator being coupled with the respective current source for the red light emitter; the green drive current correction determination block is configured to: determine a second current correction value using a second transfer function; and provide the second current correction value to a second bias generator of the plurality of bias generators, the second bias generator being coupled with the respective current source for the green light emitter; and the blue drive current correction determination block is configured to: determine a third current correction value using a third transfer function; and provide the third current correction value to a third bias generator of the plurality of bias generators, the third bias generator being coupled with the respective current source for the green light emitter.

9. The display of any of claims 1 to 8, further comprising: a first driver switch coupling a first current source of the respective current sources with the red light emitter; a second driver switch coupling a second current source of the respective current sources with the green light emitter; and a third driver switch coupling a third current source of the respective current sources with the blue light emitter.

10. A method for operating a display, the method comprising: determining an operating temperature of the display; determining, based on the operating temperature, a correction value for a drive cunent for driving a light emitter included in the display; providing the correction value to a bias generator; providing, by the bias generator based on the correction value, a bias to a current source; and providing, based on the bias, the drive current to the light emitter.

11. The method of claim 10, further comprising: sampling the drive current; and adjusting, based on the sampling, the drive current.

12. The method of claim 10 or 11, wherein determining the operating temperature of the display includes: generating an analog signal indicating the operating temperature of the display; and performing an analog to digital conversion of the analog signal to generate a digital temperature value.

13. The method of claim 12, wherein determining the correction value includes indexing a lookup table with the digital temperature value.

14. The method of claim 12, wherein determining the correction value includes calculating, based on the digital temperature value, a transfer function.

15. The method of any of claims 10 to 14, wherein the light emitter is one of a red light emitter, a green lighter emitter, or a blue light emitter of a pixel group of the display.

16. The method of any of claims 10 to 15, wherein the correction value is a first correction value, the drive current is a first drive current, the light emitter is a first light emitter, the bias generator is a first bias generator, the bias is a first bias, and the current source is a first current source. the method further comprising: determining, based on the operating temperature, a second correction value for a second drive current for driving a second light emitter included in the display; providing the second correction value to a second bias generator; providing, by the second bias generator based on the second correction value, a second bias to a second current source; providing, based on the second bias, the second drive current to the second light emitter; determining, based on the operating temperature, a third correction value for a third drive current for driving a third light emitter included in the display;providing the third correction value to a third bias generator; providing, by the third bias generator based on the third correction value, a third bias to a third current source; and providing, based on the third bias, the third drive current to the third light emitter.

17. The method of claim 16, wherein: the first light emitter is a red light emitter of a pixel of the display; the second light emitter is a green light emitter of the pixel; and the third light emitter is a blue light emitter of the pixel.

18. The method of any of claims 10 to 17, wherein the correction value indicates one of: an increase in the drive current; or a decrease in the drive cunent.

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