Apparatus, System, and Method for Dimming a Display

Abstract

Systems and methods for dimming emissive displays such as organic light emitting diode (OLED) displays. A dimming level set point signal is received. At least one dimming process is selected from four dimming processes based on the magnitude of the dimming level set point signal. The first dimming process selects a sub-range of pixel illumination levels from a range of pixel illumination levels. The second dimming process adjusts the VCOM voltage of the pixel array. The third dimming process selects between a rolling shutter and a global shutter. The fourth dimming process selectively utilizes one or more sub-pixels in the emissive display pixels based on the magnitude of the dimming level set point signal. The selected one or more dimming processes are applied to the emissive display to thereby dim the display. The display may be an OLED display.

Description

[0001] Cross - Reference to Related Applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 033,139, filed on June 1, 2020, entitled "APPARATUSES AND METHODS FOR DIMMING DISPLAYS". This patent application also claims priority to U.S. Non - Provisional Patent Application No. 17 / 334,702, filed on May 29, 2021, entitled "APPARATUSES AND METHODS FOR DIMMING DISPLAYS".

[0003] U.S. Provisional Patent Application Serial No. 63 / 033,139 is incorporated herein by reference. U.S. Non - Provisional Patent Application Serial No. 17 / 334,702 is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Technology

[0005] The present invention generally relates to displays, and more particularly to dimming organic light - emitting diode (OLED) displays. 2. Background Art

[0007] OLED display technology is developing rapidly. In particular, the development of efficient OLED materials and high - volume OLED deposition equipment has led to the large - scale commercialization of OLED displays. An OLED device has an organic semiconductor layer located between two electrodes, an anode and a cathode. The electrodes are typically made of inorganic materials. Holes and electrons are injected into the organic layer from the anode and cathode, respectively. When the electrons and holes recombine in the active organic layer, photons are emitted.

[0008] A subset of OLED displays is micro - OLED displays, which typically have a diagonal size of less than 1 inch. Micro - OLED displays generally have a backplane integrated circuit fabricated on a single - crystal silicon (Si) substrate. Since Si transistors have high performance, the pixel size for fabricating high - resolution displays in small sizes can be very small, typically equal to or less than 15 micrometers (μm). The backplane circuit system includes a pixel array, row / column drivers, video input, video processing, and programmable control means.

[0009] Micro - OLED displays are considered prime candidates for next - generation wearable products such as virtual reality (VR), augmented reality (AR), and mixed reality (MR) applications due to their small size, high resolution, low power consumption, and high video frame rate.

[0010] Depending on the given use case, some microdisplay applications require operation over a very wide range of brightness. For example, an augmented reality (AR) display must have sufficient brightness for acceptable visibility in outdoor sunlight, but must also be operable at lower brightness levels for comfortable viewing in a darker indoor environment.

[0011] Existing transmissive and reflective display technologies (e.g., liquid crystal or digital micromirror) typically decouple the light source (backlight or frontlight) from the spatial light modulator (the display panel itself). Thus, the brightness can be adjusted directly by controlling the light source, while the full dynamic range of the display can be used to control individual pixels. However, display technologies such as OLED operate by modulating the emission of light at each pixel. Different dimming methods are needed to maintain the dynamic range. This can pose problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention may best be understood by reference to the following description and the drawings used to illustrate embodiments of the invention. The invention is shown by way of example and not limitation in the figures, in which like reference numerals indicate similar elements. The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Patent Office upon request and payment of the necessary fee.

[0013] Figure 1 Shows multiple ranges of illumination information configured to dim an emissive display having a general number of brightness levels according to an embodiment of the present invention.

[0014] Figure 2 Shows multiple ranges of illumination information configured to dim an emissive display having four states reserved for brightness levels according to an embodiment of the present invention.

[0015] Figure 3 Shows a flowchart of dimming an emissive display using multiple ranges of illumination information according to an embodiment of the present invention.

[0016] Figure 4 Shows a process of dimming an emissive display using multiple ranges of illumination information according to an embodiment of the present invention.

[0017] Figure 5 Shows a flowchart of dimming an emissive display using multiple ranges of VCOM levels according to an embodiment of the present invention.

[0018] Figure 6 Shows a process of dimming an emissive display using multiple ranges of VCOM levels according to an embodiment of the present invention.

[0019] Figure 7 Shows a rolling shutter where a blackening line (K) trails an activation line (A) according to an embodiment of the present invention.

[0020] Figure 8 Shows a rolling shutter sequence with two frames and a 20% duty cycle according to an embodiment of the present invention.

[0021] Figure 9 Shows a global shutter sequence with two frames and a 20% duty cycle according to an embodiment of the present invention.

[0022] Figure 10 Shows a flowchart of dimming an emissive display using multiple shutters according to an embodiment of the present invention.

[0023] Figure 11 Shows a process of dimming an emissive display using multiple shutters according to an embodiment of the present invention.

[0024] Figure 12 Shows two sub-pixels (L-shaped) with an anode area ratio of 3:1 according to an embodiment of the present invention.

[0025] Figure 13 Shows two sub-pixels (C-shaped) with an anode area ratio of 3:1 according to an embodiment of the present invention.

[0026] Figure 14 Shows two sub-pixels (O-shaped) with an anode area ratio of 3:1 according to an embodiment of the present invention.

[0027] Figure 15 Shows a pixel circuit diagram according to an embodiment of the present invention.

[0028] Figure 16 Shows three sub-pixels with an anode area ratio of 1:2:6 according to an embodiment of the present invention.

[0029] Figure 17 Shows according to an embodiment of the present invention Figure 16 corresponding pixel circuit diagram.

[0030] Figure 18 Shows a general number of sub-pixels (O-shaped) according to an embodiment of the present invention.

[0031] Figure 19 Shows according to an embodiment of the present invention Figure 18 corresponding pixel circuit diagram.

[0032] Figure 20 Shows a flowchart of dimming an emissive display using multiple processes according to an embodiment of the present invention. Detailed Embodiments

[0033] In the following detailed description of embodiments of the present invention, reference is made to the accompanying drawings, in which like reference numerals indicate like elements and in which specific embodiments in which the invention may be practiced are shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. In other instances, well-known circuits, structures, and techniques have not been shown in detail in order not to obscure the understanding of this specification. Thus, the following detailed description is not limiting.

[0034] In various embodiments, devices, methods, and systems for dimming emissive displays such as OLED displays are described. As used in the description of this embodiment, the terms "display" and "microdisplay" will be given a broad meaning and may be used interchangeably. Note that embodiments of the present invention are applicable to displays of various sizes, including microdisplays that measure 1.5 inches or less diagonally across the display to large flat panel displays that measure several feet diagonally across the display. Thus, embodiments of the present invention are applicable to displays of any size. Additionally, as used in the description of this embodiment, it should be understood that pixels of an emissive display such as an OLED display may be composed of multiple sub-pixels, where each sub-pixel is used to provide light of a different color to the pixel. Additionally, for the purpose of dimming, a pixel may be divided into one or more sub-pixels, where each sub-pixel used for dimming is composed of sub-pixels for color. Thus, a pixel may be characterized by two levels of sub-pixels, a first level for dimming and then a second level for color. Note that the terms "pixel", "display pixel", "display element", or "OLED device" are used synonymously, and all of these terms, i.e., "pixel", "display pixel", "display element", or "OLED device", are to be distinguished from "sub-pixel". Additionally, for clarity of illustration, one or more OLED pixels will be described in the figures that follow, but it should be understood that such description extends to the entire display having many display pixels that are configured in a row and many rows, configured to provide a display having a general number of m rows and n columns of OLED display elements, on which an image is provided to a user.

[0035] In the description of this embodiment, the term "dimming ratio" is the magnitude of the white level of the display in the brightest configuration divided by the magnitude of the white level of the display in the least bright but still usable configuration. As used in the description of this embodiment, the term "dynamic range" refers to the magnitude ratio of the white-to-black ratio of the display in a given configuration. That is, the magnitude ratio of the brightest pixel level and the darkest pixel level that can be displayed simultaneously. Both ratios can conveniently be expressed in orders of magnitude (powers of 10) or bits (powers of 2). Three orders of magnitude (1000) roughly correspond to 10 bits (1024).

[0036] In various embodiments, a dimming ratio of 5 or 6 orders of magnitude (up to 20 bits) may be required in an AR application. Multiple techniques can be combined to meet the specific requirements of a given display.

[0037] In some cases, when a display can achieve a greater dynamic range than required by a given application, one technique is useful. For example, if a display can have a 12-bit dynamic range and the application requires 10 bits, then 2 bits are available for dimming. In a non-limiting example using linear coding, bright cases will use 1024 levels (0, 4, 8,... 4092), while quarter-dark cases will use 1024 levels (0, 1, 2,... 1023).

[0038] Figure 1 Generally shown at 100 are multiple ranges of illumination information configured, according to an embodiment of the present invention, to dim an emissive display having a general number of brightness levels. As used in the description of this embodiment, the term "illumination information" flexibly refers to information used to produce different brightnesses from pixels. Some non-limiting examples of illumination information can be, but are not limited to: voltages or currents used to provide different brightness values from pixels or a display formed by a pixel array, integer values in an array of values corresponding to voltages, currents, etc.

[0039] Refer to Figure 1 , the array of illumination information is indicated at 102. The first range of illumination information spans a range from zero to Z as indicated at 104. Here, zero represents the illumination information that will produce the minimum pixel brightness, and Z represents the illumination information that will produce the maximum pixel brightness. The second range of illumination information spans a range from zero to X as indicated at 106. Similarly, zero represents the illumination information that will produce the minimum pixel brightness, and X represents the illumination information that will produce the maximum pixel brightness within the range from zero to X. Note that Z is greater than X, so the range of illumination values provided by 106 is less than the range of illumination values provided by 104. Therefore, a display operating in the range 106 will be darker than when the display operates in the range 104. Conversely, a display operating in the range 104 will appear brighter than when the display operates in the range 106.

[0040] Figure 2 Generally shown at 200 are multiple ranges of illumination information configured, according to an embodiment of the present invention, to dim an emissive display that retains four states for brightness levels. Refer to Figure 2, the first range of the illumination information spans the range from zero to 4092 as indicated by 204. Here, zero represents the illumination information that will produce the minimum pixel brightness, and 4092 represents the illumination information that will produce the maximum pixel brightness. The second range of the illumination information spans the range from zero to 1023 as indicated by 206. Similarly, zero represents the illumination information that will produce the minimum pixel brightness, and 1023 represents the illumination information that will produce the maximum pixel brightness within the range from zero to 1023. If the illumination information linearly increases according to the values from zero to 4092, then the brightness in the 206 range is one-fourth of the brightness in the 204 range. Two other ranges, namely the fifty-percent bright condition and the seventy-five-percent bright condition, are included within the range from zero to 4092 but are not indicated to keep the illustration clear.

[0041] Note that in some embodiments, other multipliers (referred to herein as non-integer multipliers) are used to provide different sub-ranges of the full range of illumination information shown above using the non-limiting example of zero to 4092. For example, in Figure 2 the case shown, the forty-percent (40) condition is obtained by multiplying 1023 by the non-integer multiplier 1.6 used, such that the maximum value in the forty-percent case is 1637. Non-integer multipliers may introduce rounding, which may result in certain differential non-linearities related to the illumination information represented by the resulting ranges. However, in various cases, such differential non-linearities may be acceptable to the user.

[0042] The examples given herein are provided only for illustration and are not meant to be limiting. In some embodiments, a 12-bit dynamic range is provided, and the resulting range of illumination values is from zero to 4095, where 4095 = 2 12 - 1. In other cases, the range is scaled. For example, based on a 10-bit dynamic range, the maximum value of the range of illumination information is 1023, where 1023 = 2 10 - 1. Scaling the 10-bit range to 12 bits results in a scaled range with a maximum value of 4092.

[0043] Figure 3 Generally, a flowchart for dimming an emissive display using multiple ranges of illumination information according to an embodiment of the present invention is shown at 300. Referring to Figure 3 , a dimming input 302 is input to a selection unit 304. In one or more embodiments, the dimming input 302 is the output of a control device for adjusting the brightness of the display. The selection unit 304 receives the dimming input 302 and uses the dimming input 302 to select within the first range 306 of the illumination information up to DIM at 308 as indicated by NThe selected dimming information is used to set the parameters of the display 310 so that the brightness of the display is generated by the selected dimming information. Therefore, the dimming input 302 can increase or decrease the brightness of the display 310 depending on the value of the dimming input 302. As used herein, the variable n can be a discrete variable that can represent a set of fixed values, or it can be a continuous variable that is not limited to a set of fixed discrete values.

[0044] Figure 4 A process for dimming an emissive display using various ranges of illumination information according to an embodiment of the present invention is generally shown at 400. Figure 4 , the process begins at block 402. At block 404, a first range of illumination information is represented. When used to operate the display, the first range of illumination information corresponds to a first display brightness level. Successive ranges of illumination information are represented, such as the nth range indicated at 406, where n is a general number and depends on how much display brightness dynamic range is available for dimming. The parameter n varies depending on a given embodiment, and it can be a discrete variable representing a set of fixed values ​​or a continuous variable that is not limited to a set of fixed values. The specific examples given herein are provided for illustration only and are not meant to be limiting.

[0045] At block 408, the available range DIM1 to DIM n Select DIM i The illumination information range indicated, wherein i is selected from the range of 1 to n. At block 410, the emissive display is operated using the selected illumination information from block 408. In one or more embodiments, the emissive display is an OLED display. The process terminates at block 412.

[0046] Another technique for dimming emissive displays is to adjust the bias voltage or current common to the pixel array. For example, in a voltage-driven OLED display, the VCOM cathode voltage is adjusted to brighten or dim all pixels. When VCOM is negative, a negative VCOM voltage close to zero (e.g., -2 volts) produces darker pixels, while a negative voltage farther from zero (e.g., -4 volts) produces brighter pixels. However, the photoelectric response of OLEDs to voltage is nonlinear, and each VCOM set point must be compensated differently.

[0047] Figure 5 A flow chart for dimming an emissive display using multiple sets of VCOM levels according to an embodiment of the present invention is generally shown at 500. Figure 5, a dimming input 502 is input to a dimming selection unit 504. VCOM1 at 506 represents a VCOM setting corresponding to a particular pixel or display brightness. Similarly, an array of VCOM values is constructed, where the Mth value is represented as VCOM M The selection unit 504 selects a VCOM value from groups 506 to 508 in response to the dimming input 502. Alternatively, the selection unit may be configured to calculate a VCOM value based on the dimming input 502. Since the relationship between VCOM and pixel brightness is typically non-linear, a mathematical relationship may be used to calculate the VCOM value in response to the dimming input 502. This mathematical relationship is obtained through calibration measurements between VCOM and pixel brightness parameters such as illumination intensity, etc. The selected VCOM value is then used to operate the emissive display 510. In various embodiments, the emissive display 510 is an OLED display.

[0048] Figure 6 Generally, 600 shows a process of dimming an emissive display using multiple VCOM levels according to an embodiment of the present invention. Referring to Figure 6 , the process starts at block 602. At block 604, a first VCOM value, i.e., VCOM1, is stored. When the display is operated using VCOM1, the first VCOM level VCOM1 corresponds to a first display brightness level. Successive VCOM values are stored, such as storing the Mth value as indicated at 606, where M is a general number. At block 608, a VCOM value is selected from 602 to 604 based on the dimming input. Alternatively, at block 608, as described above in connection with Figure 5 , a VCOM value may be calculated based on the dimming input. The parameter M varies depending on the given embodiment. At block 610, the selected VCOM value from block 608 is used to operate the emissive display. In one or more embodiments, the emissive display is an OLED display. The process ends at block 612. The specific examples given herein are provided only for illustration and are not meant to be limiting.

[0049] Another technique for dimming is shutter opening and closing. Shutter opening and closing operates in the time domain and can be used for dimming control with a linear response. In various embodiments, a dimming method using both a rolling shutter and a global shutter is provided.

[0050] Dimming with a combination of global shutter and rolling shutter

[0051] Shutter opening and closing is a technique for controlling image persistence, i.e., limiting the time a pixel remains in a bright state. For example, a shutter with a 25% duty cycle means the pixel is black 75% of the time and bright 25% of the time.

[0052] Figure 7 Generally, 700 shows a rolling shutter image in which a blackening line (K) 706 trails an activation line (A) 704 according to an embodiment of the present invention. In the case of a rolling shutter, each horizontal row of the display 702 is driven to black at a fixed time after it is written with active video data. If the display scans from top to bottom, then the rolling shutter can be implemented as shown with the blackening line (K) 706 trailing the activation line (A) 704, where a portion 708 of the display is in the on state and portions 710 and 712 are in the off state. If row K 706 follows closely behind row A 704, then the duty cycle will be short, but if row K 706 lags far behind the activation line A 704, then the duty cycle will be long. Figure 1 As shown, the rolling shutter can be implemented with the blackening line (K) 706 trailing the activation line (A) 704, where a portion 708 of the display is in the on state and portions 710 and 712 are in the off state. If row K 706 follows closely behind row A 704, then the duty cycle will be short, but if row K 706 lags far behind the activation line A 704, then the duty cycle will be long.

[0053] Figure 8 Generally, 800 shows a rolling shutter sequence with two frames and a 20% duty cycle according to an embodiment of the present invention. Figure 8 For each of the two frames in, i.e., frame period 1 at 802 and frame period 2 at 822, five (5) views are shown qualitatively, which show the dimming progression of each of the two frames shown. Views 804, 806, 808, 810, and 812 depict frame period 1 802. Views 824, 826, 828, 830, and 832 depict frame period 2 822. As a non-limiting example of a rolling shutter implementation, the rolling shutter requires the K line to follow the A line at an integer row interval. The minimum interval is a single row (A - K = 1), and the next brightest will be twice as bright (A - K = 2). In one non-limiting example for illustration only and not meant to be limiting, it can be expected that a display in SXGA format (1280 × 1024) can achieve 10-bit dimming via a rolling shutter. The rolling shutter allows for continuous writing to the display and thus does not require an increased data rate.

[0054] Figure 9 Generally, 900 shows a global shutter sequence with two frames and a 20% duty cycle according to an embodiment of the present invention. When using a global shutter, all or nearly all pixels are switched on and off simultaneously. The global shutter requires the entire pixel array to be written before the illumination or "flash" period to turn the pixels on. In Figure 9In the example shown for illustration only and not meant to be limiting, the first frame period is indicated by 902. The first frame period 902 includes an off time 904 and an on time 906. During the off time, the display remains black as indicated by 908 for 80% of the frame period 902, and during the on time, the display is in the on state as indicated by 910 for 20% of the frame period 902. The 20% duty cycle indicated by the on time 906 and the off time 904 allows 80% of the frame period 902 to be used to write image data to the display. Similarly, the second frame period 912 includes an off time 914 and an on time 916. During the off time, the display remains black as indicated by 918 for 80% of the frame period 912, and during the on time, the display is in the on state as indicated by 920 for 20% of the frame period 912.

[0055] The lower the duty cycle, the shorter the on time, and the larger the duty cycle, the shorter the off time. For a 90% duty cycle, only 10% of the frame is available for writing during the off time, which requires increasing the peak input data rate by a factor of 10 during the off time.

[0056] A global shutter does not require quantizing the flash interval to an integral line interval. In some embodiments, a global shutter may require a more complex pixel design and adding one or more transistors to control the flash timing.

[0057] In various embodiments, the use of a global shutter or a rolling shutter depends on the desired duty cycle of the display. A rolling shutter is typically used with a large duty cycle (up to 100%), while a global shutter is typically used for a short duty cycle (usually less than the blanking time ratio). The blanking time is the time between the end of the first frame and the start of the second frame display. Note that a global shutter can be used for a duty cycle larger than the blanking time ratio. When this is the case, the data displayed will include some data from different frames. Depending on the image content, this may or may not be objectionable. For example, if the lower part of the display contains semiotic data that does not change much between frames, then mixing the image data from two frames may not be noticeable. However, if the image data changes significantly between frames, then mixing the data from multiple frames may be obvious, which can be avoided by restricting the use of the global shutter to a duty cycle less than the blanking time ratio.

[0058] For example, in the above SXGA format with 1024 active lines, the VESA standard specifies an additional 42 blank lines, resulting in a total of 1066 lines. When the duty cycle is less than 42 / 1066 (about 3.9%), it is beneficial to use a global shutter. In the above example, the blanking time is the time required to display 42 lines of image data. In one or more embodiments, limited by the internal switch delay, the minimum flash interval is less than one-eighth of the line period, and the minimum global shutter duty cycle is less than ((1 / 8) / 1066) = 0.01%. Therefore, more than 13-bit dimming can be achieved. Additionally, importantly, the same implementation allows the global shutter duty cycle to increase in fine increments based on the pixel clock, such that the second darkest setting is only slightly brighter than the minimum duty cycle setting.

[0059] In one or more embodiments, when the desired duty cycle is between the duty cycle of the maximum global shutter (42 / 1066 in the SXGA example) and the duty cycle of the minimum rolling shutter (1 / 1066), either method can be used.

[0060] In some embodiments of dimming using multiple shutters, a given dimming value may not produce exactly the same dimming for both types of shutters, so artifacts such as flicker may occur when transitioning from one shutter type to the other. Therefore, if the same threshold (duty cycle value) is used for switching from a rolling shutter to a global shutter when the duty cycle decreases and from a global shutter to a rolling shutter when the duty cycle increases, then if the dimming control switches directly at that duty cycle value, it may exhibit flicker and cause annoyance to the user. This problem is alleviated by using different duty cycle values for the switching thresholds. In one or more embodiments, hysteresis control can be used, i.e., the threshold for switching from a rolling shutter to a global shutter is set lower than the threshold for switching from a global shutter to a rolling shutter.

[0061] A non-limiting example of a multi-threshold system configuration applicable to the above SXGA display example is to set the transition from a rolling shutter to a global shutter at a 2% duty cycle and the transition from a global shutter to a rolling shutter at a 3% duty cycle. Other values are possible, and the specific values are provided only for illustration and do not imply limitation.

[0062] Figure 10 Generally, a flowchart of dimming an emissive display using multiple shutters according to an embodiment of the present invention is shown at 1000. Refer to Figure 10, a dimming input 1002 is input to a dimming selection unit 1004. The rolling shutter parameter at 1006 is for a certain range of the dimming input 1002. Similarly, the global shutter parameter at 1008 is for a certain range of the dimming input 1002. In response to the dimming input 1002, the selection unit 1004 selects a shutter parameter from 1006 to 1008. Then the selected shutter parameter is used to operate the emissive display 1010. In various embodiments, the emissive display 1010 is an OLED display.

[0063] Figure 11 Generally, a process of dimming an emissive display using multiple shutters according to an embodiment of the present invention is shown at 1100. Refer to Figure 11 , the process starts at block 1102. At block 1104, rolling shutter parameters are established for a given display. At block 1106, global shutter parameters are established for a given display. At block 1108, either the rolling shutter or the global shutter is selected for dimming the display. As described above, the type of shutter used depends on the desired dimming value and the display duty cycle. At block 1110, at the dimming value, the display is operated with the selected shutter suitable for that dimming value. The process stops at block 1112.

[0064] Dimming with sub-pixels

[0065] In various embodiments, in the spatial domain, sub-pixels can be used to control the emission area of each pixel for dimming control. Note that each sub-pixel can also include separate sub-pixels for color generation. In some embodiments, color sub-pixels are divided into sub-pixels for dimming. This division simplifies the circuit for driving the sub-pixels. For example, a common write device and a common storage device can be used among the dimming sub-pixels within a given color sub-pixel. As used in the description of this embodiment, the terms "blocked" and "sub-" are used synonymously. For example, blocked pixels, sub-pixels, and blocked sub-pixels can refer to the same structure. Note that in some embodiments, display information is provided by using a single color known in the art as grayscale. Any color can be used to provide a "grayscale" display, such as but not limited to gray, green, red, blue, etc. Sub-pixel dimming in the spatial domain enables linear dimming control.

[0066] In one or more embodiments, as a non-limiting example given for illustration and not meant to be limiting, two sub-pixels with a brightness ratio of 3:1 are utilized, but it should be understood that multiple sub-pixels and other ratios can be used. Figure 12 Generally, two sub-pixels with an area ratio of 3:1 according to an embodiment of the present invention are shown at 1200.

[0067] In emissive displays such as OLED displays, it can be expected that two sub-pixels driven at the same voltage have a brightness proportional to their anode areas. Figure 12 Pixel 1202 is shown, which has a first sub-pixel 1204 and a second sub-pixel 1206, and the two sub-pixels together have an anode area ratio of 3:1. In this configuration, the smaller sub-pixel 1206 is shown as a square, and the larger pixel 1204 is shown as an L-shape. It should be appreciated that other shapes are possible and may be preferred for other applications. In various embodiments, Figure 12 The sub-pixel structure shown can be used for full-color pixels composed of individual color sub-pixels (such as red, green, blue sub-pixels), or the sub-pixel structure can be used to provide grayscale displays.

[0068] Note that the larger sub-pixel 1204 is a nominal L-shape with two long sides. Bisectors placed perpendicular to each of the two long sides at the midpoint of each of the two long sides intersect at a center point. Similarly, bisectors placed perpendicular to each of the two vertical sides of the smaller sub-pixel 1206 at the midpoint of each of the two sides intersect at a center point. The bisectors of the larger sub-pixel 1204 are not collinear with the bisectors of the smaller sub-pixel 1206. The non-collinear bisectors cause the intersection point of the bisectors of the larger sub-pixel 1204 to be offset from the intersection point of the bisectors of the smaller sub-pixel 1206. The offset in the X direction is indicated by 1210 (ΔX), and the offset in the Y direction is indicated by 1208 (ΔY). The L-shaped sub-pixel configuration causes a smaller image offset in both the X and Y directions as indicated.

[0069] In operation, when both the larger sub-pixel 1204 and the smaller sub-pixel 1206 are in the on state, a pixel array such as the L-shaped sub-pixel bright array shown at 1230 will appear. The darkest setting of the L-shaped sub-pixel array is achieved by placing the larger sub-pixel (e.g., 1204) in the off state and the smaller sub-pixel (e.g., 1206) in the on state, as in the L-shaped sub-pixel dim array shown at 1260. A third brightness setting (not shown) is achieved by placing the larger sub-pixel (e.g., 1204) in the on state and the smaller sub-pixel (e.g., 1206) in the off state.

[0070] Figure 13 Two sub-pixels (C-shaped) with an anode area ratio of 3:1 according to an embodiment of the present invention are shown. Refer to Figure 13 , in this configuration, the smaller sub-pixel 1306 is shown as a square, and the larger pixel 1304 is shown as a C-shape. It should be appreciated that other shapes are possible and may be preferred for other applications. In various embodiments, Figure 13The sub-pixel structure shown can be used for full-color pixels composed of respective color sub-pixels (such as red, green, blue sub-pixels), or the sub-pixel structure can be used to provide grayscale display.

[0071] Note that the larger sub-pixel 1304 is a nominal C shape with three long sides. Bisectors placed perpendicular to each of the two long sides at the midpoint of each of the two long sides intersect at a central point. Similarly, bisectors placed perpendicular to each of the two vertical sides of the smaller sub-pixel 1306 at the midpoint of each of the two sides intersect at a central point. The bisectors of the larger sub-pixel 1304 are not collinear with the bisectors of the smaller sub-pixel 1306. The non-collinear bisectors cause the intersection point of the bisectors of the larger sub-pixel 1304 to be offset from the intersection point of the bisectors of the smaller sub-pixel 1306. The offset in the X direction is indicated by 1310 (ΔX). The C-shaped sub-pixel configuration causes a smaller image shift to occur only in one direction (i.e., the X direction as indicated).

[0072] In operation, when both the larger sub-pixel 1304 and the smaller sub-pixel 1306 are in the on state, a pixel array such as the C-shaped sub-pixel bright array shown at 1330 will appear. The darkest setting of the C-shaped sub-pixel array is achieved by placing the larger sub-pixel (e.g., 1304) in the off state and the smaller sub-pixel (e.g., 1306) in the on state, as in the C-shaped sub-pixel dim array shown at 1360. A third brightness setting (not shown) is achieved by placing the larger sub-pixel (e.g., 1304) in the on state and the smaller sub-pixel (e.g., 1306) in the off state.

[0073] Figure 14 Two sub-pixels (O shape) with an anode area ratio of 3:1 according to an embodiment of the present invention are shown. Refer Figure 14 , in this configuration, the smaller sub-pixel 1406 is shown as a square, and the larger pixel 1304 is shown as an O shape. It should be recognized that other shapes are possible and may be preferred for other applications. In various embodiments, Figure 14 The sub-pixel structure shown can be used for full-color pixels composed of respective color sub-pixels (such as red, green, blue sub-pixels), or the sub-pixel structure can be used to provide grayscale display.

[0074] Note that the larger sub-pixel 1404 is a nominal O shape with four long sides. Bisectors placed perpendicular to each of the two long sides at the midpoint of each of the two long sides intersect at the center point. Similarly, bisectors placed perpendicular to each of the two perpendicular sides of the smaller sub-pixel 1406 at the midpoint of each of the two sides intersect at the center point. The bisectors of the larger sub-pixel 1404 are collinear with the bisectors of the smaller sub-pixel 1406. The collinear bisectors cause the intersection point of the bisectors of the larger sub-pixel 1304 and the intersection point of the bisectors of the smaller sub-pixel 1306 to be the same point. Thus, there is no image shift in either the X direction or the Y direction.

[0075] In operation, when both the larger sub-pixel 1404 and the smaller sub-pixel 1406 are in the on state, a pixel array such as the bright O-shaped sub-pixel array shown at 1430 will appear. The darkest setting of the O-shaped sub-pixel array is achieved by turning the larger sub-pixel (e.g., 1404) off and the smaller sub-pixel (e.g., 1406) on, as in the dim O-shaped sub-pixel array shown at 1460. A third brightness setting (not shown) is achieved by turning the larger sub-pixel (e.g., 1404) on and the smaller sub-pixel (e.g., 1406) off.

[0076] Figure 15 A pixel circuit diagram according to an embodiment of the present invention is shown. Referring Figure 15 , a circuit diagram representing a pixel having two sub-pixels for dimming (such as Figure 12 , Figure 13 or Figure 14 shown in any one of the sub-pixels) is shown. In the following discussion, when referring to a complementary metal oxide semiconductor (CMOS) implementation, it is not meant to be limiting. In various embodiments, the backplane circuit architecture for driving pixels of an emissive display uses a pair of write transistors (PMOS and NMOS) indicated by CMOS devices 1512 to charge the storage capacitor 1514 from the column line 1506. In a write operation, control lines 1508 and 1510 are used to charge the storage capacitor 1514 to the voltage of the column line 1506. The voltage on the storage capacitor 1514 allows current to flow through the sub-pixel transistors 1516a and 1516b. The first switch transistor 1522a is operated by the control line 1520a. When the switch transistor 1522a is switched on, current flows through the smaller emissive sub-pixel, and the emissive region 1502a of the smaller sub-pixel emits light. The smaller sub-pixel can be, for example, any one of the smaller sub-pixels such as 1206 ( Figure 12 ), 1306 ( Figure 13 ) or 1406 ( Figure 14 ).

[0077] Similarly, the second switching transistor 1522b is operated by the second control line 1520b. When the second switching transistor 1522b is switched on, current flows through the larger emitter sub-pixel, and the emission region 1502b of the larger sub-pixel emits light. The larger sub-pixel can be, for example, any one of the larger sub-pixels such as 1204( Figure 12 ), 1304( Figure 13 ), or 1404( Figure 14 ).

[0078] When both switching transistors (1522a and 1522b) are in the on state, both the smaller sub-pixel and the larger sub-pixel emit light. This state is shown at 1230( Figure 12 ), 1330( Figure 13 ), or 1430( Figure 14 ). In various embodiments, the voltage of the column line 1506 is established using the illumination information described in connection with the above figures.

[0079] Thus, in one or more embodiments, two sub-pixels share a common storage capacitor 1514, and thus these two sub-pixels are driven to the same level. Since there is only one storage node 1514 and one column line Cn 1506, the power required to drive these two sub-pixels does not exceed that required for a single pixel having the same total area. The different switching transistors (1522a and 1522b) are driven by signals F1n and F3n, respectively. In the bright mode, both switching transistors (1522a and 1522b) will be enabled, but in the dim mode, the switching transistor 1522b for the larger sub-pixel will remain off. In this way, the bright mode is 4 times brighter than the dim mode, and a 2-bit dimming ratio is achieved.

[0080] In one or more embodiments, the driving transistor and the switching transistor are scaled to match the anode area ratio such that the drawn size of the larger transistor is 3 times that of the smaller transistor, thereby providing the same current density in the two sub-pixels. In still other embodiments, the driving transistor and the switching transistor are drawn in sizes similar to those of the sub-pixels. The sizes of the driving transistor and the switching transistor of the sub-pixel can be adjusted according to the constraints of a given implementation of the integrated circuit as needed.

[0081] The switching signals F3n and F1n are also used in the global shutter mode to enable the pixel during the flash period.

[0082] Figure 16 Generally, three sub-pixels with an anode area ratio of 1:2:6 according to an embodiment of the present invention are shown at 1600. Refer to Figure 16, in this configuration, the smaller sub-pixel 1608 is shown as a square, the medium-sized sub-pixel 1606 is shown as a rectangle, and the larger pixel 1604 is shown as a rectangle. It should be recognized that other shapes are possible and may be preferred for other applications. It is also recognized that more than three sub-pixels as described herein may be provided. In various embodiments, Figure 16 The sub-pixel structure shown can be used for full-color pixels composed of respective color sub-pixels (such as red, green, and blue sub-pixels), or the sub-pixel structure can be used to provide a grayscale display.

[0083] Using the ternary sub-pixels shown at 1600, various dimming states can be achieved. The maximum brightness state is shown at 1630, in which all three sub-pixels (1608, 1606, and 1604) are in the on state. The darkest state is shown at 1690, in which only the smallest sub-pixel 1608 is in the on state. One of several medium states is shown at 1660, in which the smallest sub-pixel 1608 and the medium-sized sub-pixel 1606 are in the on state while the largest sub-pixel 1604 is in the off state.

[0084] Figure 17 Generally shown at 1700 is a pixel circuit diagram corresponding to an embodiment of the present invention and Figure 16 corresponding. Referring to Figure 17 , a circuit diagram representing a pixel having three sub-pixels for dimming (such as Figure 16 sub-pixels) is shown. In the following discussion, when referring to a complementary metal oxide semiconductor (CMOS) implementation, it is not meant to be limiting. In various embodiments, the backplane circuit system architecture for driving the pixels of an emissive display utilizes a pair of write transistors (PMOS and NMOS) indicated by CMOS devices 1712 to charge the storage capacitor 1714 from the column line 1706. In a write operation, the control lines 1708 and 1710 are used to charge the storage capacitor 1714 to the voltage of the column line 1706. The voltage on the storage capacitor 1714 allows current to flow through the sub-pixel transistors 1716a, 1716b, and 1716c. The first switch transistor 1722a is operated by the first control line 1720a. When the first switch transistor 1722a switches to the on state, current flows through the smallest emissive sub-pixel, and the emissive region 1702a of the smallest sub-pixel emits light. The smallest sub-pixel can be a sub-pixel such as 1608 ( Figure 16 ).

[0085] Similarly, the second switching transistor 1722b is operated by a second control line 1720b. When the second switching transistor 1722b is switched on, current flows through the medium-sized emitting sub-pixel, and the emission region 1702b of the medium-sized sub-pixel emits light. The medium-sized sub-pixel can be, for example, 1606( Figure 16 ).

[0086] Similarly, the third switching transistor 1722c is operated by a third control line 1720c. When the third switching transistor 1722c is switched on, current flows through the largest emitting sub-pixel, and the emission region 1702c of the largest sub-pixel emits light. The largest sub-pixel can be, for example, 1604( Figure 16 ).

[0087] In one or more embodiments, the driving transistors and the switching transistors are scaled to match the anode area ratio such that the drawn size of the larger transistor is 6 times that of the smaller transistor, thereby providing the same current density in all sub-pixels. In still other embodiments, the driving transistors and the switching transistors are drawn in dimensions similar to the dimensions of all sub-pixels. The dimensions of the driving transistors and the switching transistors of the sub-pixels can be adjusted according to the constraints of a given implementation of the integrated circuit as needed.

[0088] The switching signals F1n (1720a), F2n (1720b), and F6n (1720c) are also used in the global shutter mode to enable the sub-pixels during the flash period. In various embodiments, the irradiation information described in connection with the above figure is used to establish the voltage of the column line 1706.

[0089] Figure 18 Generally, a general number of sub-pixels (O-shaped in this example) according to an embodiment of the present invention are shown at 1800. Referring to Figure 18 , the pixel 1802 is constructed of a general number of O-shaped sub-pixels. The first non-emission region 1804 defines the geometry of the pixel. The first sub-pixel 1806 is defined by the second non-emission region 1808 and the first non-emission region 1804. Similarly, the second sub-pixel 1810 is defined by the second non-emission region 1808 and the third non-emission region 1812. Finally, the general sub-pixel 1818 is defined by the last emission region 1816. Thus, a general number of sub-pixels are created for a given pixel. Note that sub-pixel shapes other than the Figure 18 shown O-shaped will also be used in other embodiments.

[0090] Figure 19 Generally, a pixel circuit diagram corresponding to Figure 18 according to an embodiment of the present invention is shown at 1900. Referring to Figure 19, shows a circuit diagram of a pixel representing a pixel having a general number m of sub-pixels for dimming, such as Figure 18 of the sub-pixels). In the following discussion, when referring to embodiments of complementary metal oxide semiconductor (CMOS), it is not meant to be limiting. In various embodiments, the backplane circuit architecture for driving the pixels of an emissive display utilizes a pair of write transistors (PMOS and NMOS) indicated by CMOS device 1912 to charge the storage capacitor 1914 from the column line 1906. In a write operation, the control lines 1908 and 1910 are used to operate the CMOS device 1912 to charge the storage capacitor 1914 to the voltage of the column line 1906. The voltage on the storage capacitor 1914 allows current to flow through the sub-pixel transistors 1916a to 1916m. The first switch transistor 1922a is operated by the first control line 1920a. When the first switch transistor 1922a is switched on, current flows through the smallest emissive sub-pixel, and the emission region 1902a of the smallest sub-pixel emits light. The smallest sub-pixel can be, for example, 1818 ( Figure 18 ).

[0091] Similarly, the m-th switch transistor 1922m is operated by the m-th control line 1920m. When the m-th switch transistor 1922m is switched on, current flows through the m-th emissive sub-pixel, and the emission region 1902m of the m-th sub-pixel emits light. The m-th sub-pixel can be, for example, 1806 ( Figure 18 ).

[0092] In one or more embodiments, the drive transistors and the switch transistors are scaled to match the anode area ratio such that the size of the larger drawn transistor is m times that of the smallest transistor, thereby providing the same current density in all sub-pixels. In still other embodiments, the drive transistors and the switch transistors are drawn in dimensions similar to the dimensions of all sub-pixels. The dimensions of the drive transistors and the switch transistors of the sub-pixels can be adjusted according to the constraints of a given integrated circuit implementation as needed.

[0093] The switch signals F1n (1920a) to F1mn (1920m) are also used in the global shutter mode to enable the pixels during the flash period. In various embodiments, the voltage of the column line 1906 is established using the illumination information described in conjunction with the above figure.

[0094] In various embodiments, depending on the amount of dimming desired for a given display and application, multiple dimming techniques are applied to an emissive display such as an OLED display.

[0095] Figure 20 Generally, a flowchart of dimming an emissive display using multiple processes according to an embodiment of the present invention is shown at 2000. Refer to Figure 20, the dimming input 2002 is input to the dimming logic / control unit 2004. One or more of the above four dimming techniques are selected by the dimming logic / control unit 2004 and used to dim the emissive display 2014. The first dimming technique 2006 uses a portion of the dynamic range of pixel brightness for dimming. The second dimming technique 2008 adjusts the VCOM of all pixels for dimming. The third dimming technique 2010 selects a shutter method, i.e., a rolling shutter or a global shutter. The fourth dimming technique 2012 adjusts the emissive area of ​​the display pixel by turning the sub-pixel on or off.

[0096] These four dimming techniques 2006, 2008, 2010 and 2012 can be used alone or in any combination to dim the pixels of an emissive display such as an OLED display. In some use cases, the display is used in an extremely low backlight environment, such as during the night or in an environment that exists in a room with insufficient or no light. In such a low ambient light environment, the display can be used to provide image information from a night vision camera, which image information, for example, cannot be seen by the user with the naked eye. In such an environment, it is desirable to maximize the dynamic range of the display while paying attention to not blinding the user due to the display brightness being set too high. Therefore, in some embodiments, process 206 is not used to maximize the dynamic range to present image information. Process 2008 will use a larger negative VCOM voltage (approximately -1.5 volts to -2 volts) to dim the pixel. Process 210 will be set to dim the pixel using a global shutter with a short duty cycle. Process 212 will be set to enable the smallest sub-pixel area or the low-end sub-pixel area. So configured, the display can be used for night vision to provide a high dynamic range image without blinding the user by making the display too bright.

[0097] At the other end of the spectrum is the full daylight intensity use case, i.e., the display is used during daylight hours. Thus, in some embodiments, in this use case, the display may be used to display symbology information such as alphanumeric characters to the user, rather than displaying image information (e.g., land topography). The dynamic range may be sacrificed, and only the high end (or equivalently, the bright end) of the dynamic range is required to display alphanumeric symbology characters. Thus, process 2006 is used to give up some dynamic range to increase display brightness. Only a few bits of dynamic range are required. Process 2008 is used to increase the brightness of the display pixels by setting VCOM to a smaller negative number. In some embodiments, this means making VCOM approximately equal to, for example, -4 volts. Process 2010 operates the display at a high duty cycle by using, for example, a rolling shutter to facilitate display brightness. Process 2012 is configured to enable all pixel areas to facilitate display brightness.

[0098] Thus, in various configurations, techniques for dimming are combined to provide a very large dimming range for emissive displays such as, for example, OLED displays. Note that other combinations of the dimming techniques listed above can be combined in various embodiments of the present invention. Two use cases are described, one for night mode and the other for day mode. However, as the ambient light level changes, the four dimming processes 2006, 2008, 2010, and 2012 are used in various combinations and configurations to provide a display that conveys information to the user without dazzling the user or presenting incomprehensible information.

[0099] In various embodiments, the OLED system and components of the OLED system described in the previous figures are implemented in an integrated circuit device, which may include an integrated circuit package that contains an integrated circuit. In some embodiments, the components of the system and the system are implemented in a single integrated circuit die. In other embodiments, the components of the system and the system are implemented in more than one integrated circuit die of an integrated circuit device, which may include a multi-chip package that contains an integrated circuit. In some embodiments, the OLED display and the OLED display backplane circuitry are implemented on the same integrated circuit chip.

[0100] For the purposes of discussing and understanding the embodiments of the present invention, it should be understood that those skilled in the art use various terms to describe techniques and methods. In addition, in the description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to those of ordinary skill in the art that the embodiments of the present invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form without being shown in detail in order to avoid obscuring the embodiments of the present invention. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice the present invention, and it should be understood that other embodiments may be utilized and logical, mechanical, electrical, and other changes may be made without departing from the scope of the embodiments of the present invention.

[0101] Some portions of the description may be presented in terms of algorithms and symbolic representations of operations on data bits within, for example, a computer memory. These algorithmic descriptions and representations are the means by which those of ordinary skill in the data processing arts most effectively convey the substance of their work to others of ordinary skill in the same field. An algorithm is here, and generally, conceived as a self-consistent sequence of acts leading to a desired result. These acts are steps requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. For the sake of common usage, it has proven convenient at times to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, waveforms, data, time series, etc.

[0102] However, it should be borne in mind that all such terms and similar terms are to be associated with appropriate physical quantities and are merely convenient labels applied to those quantities. Unless otherwise expressly stated, as will be apparent from the discussion herein, it should be recognized that: throughout this specification, discussions using terms such as "processing" or "manipulating" or "computing" or "determining" or "displaying" etc. can refer to the actions and processes of a computer system or similar electronic computing device that manipulates and transforms data represented as physical (electronic) quantities within the computer system registers and memory into other data similarly represented as physical quantities within the computer system memory or registers or other such information storage, transmission, or display devices.

[0103] It should be understood that those skilled in the art use various terms and techniques to describe communications, protocols, applications, implementations, mechanisms, etc. One such technique is to describe the implementation of a technique in terms of an algorithm or mathematical expression. That is, while the technique may be implemented, for example, as code executed on a computer, the expression of the technique may be more appropriately and concisely conveyed and communicated as a formula, algorithm, mathematical expression, flow diagram, or flowchart. Thus, those of ordinary skill in the art will recognize that a block representing A + B = C is an addition function, the implementation of which in hardware and / or software will take two inputs (A and B) and produce a sum output (C). Accordingly, the use of a formula, algorithm, or mathematical expression as a description should be understood to have at least a physical embodiment in hardware and / or software (such as a computer system in which the techniques of the invention may be practiced and implemented as an embodiment).

[0104] A non-transitory machine-readable medium should be understood to include any mechanism that stores information in a machine (e.g., computer) readable form. For example, a machine-readable medium (synonymously referred to as a computer-readable medium) includes read-only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; except for the transmission of information via propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.); and so on.

[0105] Accordingly, embodiments of the present invention can be used to provide a dimmable high-brightness OLED display. Some non-limiting examples of OLED systems using embodiments of the present invention are: mobile phones, large-screen displays, use in near-eye (NTE) displays or head-mounted computing devices, but are not limited thereto. Other embodiments of the present invention can be easily implemented in generally configured wearable or head-wearable devices, such as but not limited to: wearable products such as virtual reality (VR), augmented reality (AR), mixed reality (MR), etc.; wristbands, watches, glasses, goggles, masks, headbands, helmets, etc. In the description of this embodiment, wearable encompasses head-wearable, wrist-wearable, neck-wearable, and thus any form of wearable that can be applied to a user.

[0106] As used in this specification, "an embodiment" or "embodiments" or similar phrases mean that the described feature(s) are included in at least one embodiment of the present invention. The mention of "an embodiment" in this specification does not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive either. "An embodiment" also does not mean that there is only a single embodiment of the present invention. For example, the features, structures, actions, etc. described in "an embodiment" can also be included in other embodiments. Accordingly, the present invention can include various combinations and / or integrations of the embodiments described herein.

[0107] Although the present invention has been described in accordance with several embodiments, those skilled in the art will recognize that the present invention is not limited to the described embodiments, but can be practiced with modifications and variations within the spirit and scope of the appended claims. Accordingly, the description is to be regarded as illustrative rather than restrictive.

Claims

1. A method for dimming an OLED display, comprising: Receiving a dimming level set point signal as an input; Establishing a selected duty cycle based on the dimming level set point signal; When the selected duty cycle is within a range from a first lower limit to 100% duty cycle, dimming the OLED display using a rolling shutter; And When the selected duty cycle is within a range from a second lower limit to the minimum duty cycle for the OLED display, dimming the OLED display using a global shutter; Wherein the first lower limit is for switching from the rolling shutter to the global shutter when the duty cycle decreases, the second lower limit is for switching from the global shutter to the rolling shutter when the duty cycle increases, the first lower limit is less than the second lower limit, and both the first lower limit and the second lower limit are less than the blanking time of the OLED display.

2. The method according to claim 1, wherein, The increment on the global shutter is established by pixel clock cycles.

3. The method according to claim 1, further comprising: Selecting a sub - range of pixel illumination information from a range of pixel illumination information, wherein the range spans a larger range of luminance levels than the sub - range, and the selection is made based on the amplitude of the dimming level set point signal; and Driving the OLED display pixels using the sub - range.

4. A non - transitory computer - readable storage medium storing program code for causing a data processing system to perform steps including: Receiving a dimming level set point signal as an input; Establishing a selected duty cycle based on the dimming level set point signal; When the selected duty cycle is within a range from a first lower limit to 100% duty cycle, dimming the OLED display using a rolling shutter; And When the selected duty cycle is within a range from a second lower limit to the minimum duty cycle for the OLED display, dimming the OLED display using a global shutter, wherein the first lower limit is for switching from the rolling shutter to the global shutter when the duty cycle decreases, the second lower limit is for switching from the global shutter to the rolling shutter when the duty cycle increases, the first lower limit is less than the second lower limit, and both the first lower limit and the second lower limit are less than the blanking time of the OLED display.

5. The non - transitory computer - readable storage medium according to claim 4, wherein the increment on the global shutter is established by pixel clock cycles.

6. The non - transitory computer - readable storage medium according to claim 4, further comprising: Selecting a sub - range of pixel illumination information from a range of pixel illumination information, wherein the range spans a larger range of luminance levels than the sub - range, and the selection is made based on the amplitude of the dimming level set point signal; and Driving the OLED display pixels using the sub - range.

7. The non - transitory computer - readable storage medium according to claim 4, further comprising: Adjusting the VCOM voltage of the OLED display based on the dimming level set point.

8. A non - transitory computer - readable storage medium storing program code for causing a data processing system to perform steps including: Receive a dimming level set point; Select a sub-range of pixel illumination levels from a range of pixel illumination levels based on the dimming level set point; Adjust the VCOM voltage of the OLED display based on the dimming level set point; Establish a selected duty cycle based on the dimming level set point signal; When the selected duty cycle is within a range from a first lower limit to 100% duty cycle, dim the OLED display using a rolling shutter; When the selected duty cycle is within a range from a second lower limit to the minimum duty cycle for the OLED display, dim the OLED display using a global shutter, wherein the first lower limit is used to switch from the rolling shutter to the global shutter as the duty cycle decreases, the second lower limit is used to switch from the global shutter to the rolling shutter as the duty cycle increases, the first lower limit is less than the second lower limit, and both the first lower limit and the second lower limit are less than the blanking time of the OLED display; and Illuminate one or more segments in each segmented pixel of the OLED display, each segmented pixel including: At least a first emission region; At least a second emission region; and A non-emission region disposed between the at least first emission region and the at least second emission region, and in operation, dim the OLED display based on the dimming level set point.

9. A method for dimming an OLED display, comprising: Receive a dimming level set point; Select a sub-range of pixel illumination levels from a range of pixel illumination levels based on the dimming level set point; Adjust the VCOM voltage of the OLED display based on the dimming level set point; Establish a selected duty cycle based on the dimming level set point signal; When the selected duty cycle is within a range from a first lower limit to 100% duty cycle, dim the OLED display using a rolling shutter; When the selected duty cycle is within a range from a second lower limit to the minimum duty cycle for the OLED display, dim the OLED display using a global shutter, wherein the first lower limit is used to switch from the rolling shutter to the global shutter as the duty cycle decreases, the second lower limit is used to switch from the global shutter to the rolling shutter as the duty cycle increases, the first lower limit is less than the second lower limit, and both the first lower limit and the second lower limit are less than the blanking time of the OLED display; and Illuminate one or more segments in each segmented pixel of the OLED display, each segmented pixel including: At least a first emission region; At least a second emission region; and A non-emission region disposed between the at least first emission region and the at least second emission region, and in operation, dim the OLED display based on the dimming level set point.

Images