Patent Application
20250131888
This disclosure relates generally to display drivers, and more particularly to source amplifier control for reducing power consumption in display drivers.
A display driver of a panel display device, such as an organic light emitting diode (OLED) display device, a micro light emitting diode (LED) display device, and a liquid crystal display (LCD) device, may use source amplifiers to drive source lines (also referred to as data lines) of the display panel. In a typical implementation, the source amplifiers may be configured to generate data voltages corresponding to pixel data and provide the data voltages to pixels of the display panel to drive or update the pixels with the data voltages.
In some implementations, the source amplifiers may further be used to drive the source lines at a desired voltage level during blanking periods. For example, in implementations where pixels of a display panel may suffer from charge leakage from storage capacitors thereof during blanking periods, the source amplifiers may drive the source lines at a predetermined voltage during the blanking periods to suppress or eliminate charge leakage from the storage capacitors.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below. This summary is not necessarily intended to identify key features or essential features of the present disclosure. The present disclosure may include the following various aspects and embodiments.
In an exemplary embodiment, the present disclosure provides a display driver. The display driver includes a first source output, a second source output, a first source amplifier, a second source amplifier, and a first switch. The first and second source outputs are coupled to a display panel. The first source amplifier is configured to provide a first data voltage to the first source output based on first pixel data during a display update period and provide a predetermined voltage to the first source output during a non-display update period. The second source amplifier is configured to provide a second data voltage to the second source output based on second pixel data during the display update period. The first switch is configured to electrically connect an output of the first source amplifier to the second source output to provide the predetermined voltage to the second source output during the non-display update period. The second source amplifier is configured to be deactivated during the non-display update period.
In another exemplary embodiment, the present disclosure provides a display device. The display device includes a display panel and a display driver. The display driver includes a first source output, a second source output, a first source amplifier, a second source amplifier, and a first switch. The first and second source outputs are coupled to the display panel. The first source amplifier is configured to provide a first data voltage to the first source output based on first pixel data during a display update period and provide a predetermined voltage to the first source output during a non-display update period. The second source amplifier is configured to provide a second data voltage to the second source output based on second pixel data during the display update period. The first switch is configured to electrically connect an output of the first source amplifier to the second source output to provide the predetermined voltage to the second source output during the non-display update period. The second source amplifier is configured to be deactivated during the non-display update period.
In yet another exemplary embodiment, the present disclosure provides a method. The method includes providing, by a first source amplifier, a first data voltage to a first source output based on first pixel data during a display update period, wherein the first source output is coupled to a display panel. The method further includes providing, by a second source amplifier, a second data voltage to a second source output based on second pixel data during the display update period, wherein the second source output is coupled to the display panel. The method further includes providing, by the first source amplifier, a predetermined voltage to the first source output during a non-display update period. The method further includes electrically connecting the output of the first source amplifier to the second source output to provide the predetermined voltage to the second source output during the non-display update period. The method further includes deactivating the second source amplifier during the non-display update period.
Other features and aspects are described in more detail below with reference to the accompanying drawings.
To facilitate understanding, identical reference numerals have been used, where possible, to designate elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be utilized in other embodiments without specific recitation. Suffixes may be added to reference numerals for distinguishing elements from one another. The drawings referred to herein should not be understood as being drawn to scale unless specifically noted. Also, the drawings are often simplified and details or components are omitted for clarity of presentation and explanation. The drawings and discussion serve to explain principles discussed below.
The following detailed description is exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding background, summary and brief description of the drawings, or in the following detailed description.
In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the disclosed technology. However, it will be apparent to one of ordinary skill in the art that the disclosed technology may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.
The term “coupled” as used herein means connected directly to or connected through one or more intervening components or circuits. Further, throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as by the use of the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.
As discussed above, a display driver of a panel display device, such as an OLED display device, a micro-LED display device, and an LCD device, may use source amplifiers to drive source lines of the display panel. In a typical implementation, the source amplifiers may be configured to generate data voltages corresponding to pixel data and provide the data voltages to pixels of the display panel to drive or update the pixels with the data voltages. In some implementations, the source amplifiers may further be used to drive the source lines at a desired voltage level during blanking periods. More specifically, in implementations where pixels of the display panel may suffer from charge leakage from storage capacitors thereof during blanking periods, the source amplifiers may drive the source lines at a predetermined voltage during blanking periods to suppress or eliminate charge leakage from the storage capacitors.
With recent increases in the display resolution, a display driver may incorporate an increased number of source amplifiers. Since source amplifiers may consume significant power, the uses of an increased number of source amplifiers may undesirably increase the power consumption of the display device. Accordingly, there is a technical need to reduce the power consumption of the source amplifiers. Presented below are embodiments of the present disclosure which suppress or eliminate charge leakage from storage capacitors in pixels while reducing power consumption of the source amplifiers.
In the shown embodiment, the display panel 100 includes an array of pixels 110, a gate scan driver 120, an emission scan driver 130, a set of gate lines G [1] to G [n], a set of emission lines EM [1] to EM [n], and a set of source lines SL [1] to SL [m]. Each pixel 110 is coupled to a corresponding gate line G [i], a corresponding emission line EM [i], and a corresponding source lines SL [j], where i is a natural number between 1 and n, inclusive, and j is a natural number between 1 and m, inclusive. The gate lines G [1] to G [n] are coupled to the gate scan driver 120, and the emission lines EM [1] to EM [n] are coupled to the emission scan driver 130. The source lines SL [1] to SL [m] are coupled to source outputs S [1] to S [m] of the display driver 200.
The pixels 110 are each configured to be driven or updated with a data voltage received from the display driver 200. In one or more embodiments, driving or updating a pixel 110 coupled to the gate line G [i], the emission line EM [i], and the source line SL [j] may be accomplished by asserting the gate line G [i] in a state in which the emission line EM [i] is deasserted and a data voltage is supplied to the source line SL [j]. The pixels 110 are each further configured to emit light with a luminance level corresponding to the data voltage received from the display driver 200. The light emission from the pixels 140 is controlled by the emission lines EM [1] to EM [N]. The pixels 110 coupled to the emission line EM [i] are configured to emit light when the emission line EM [i] is asserted and not to emit light when the emission line EM [i] is deasserted. The gate scan driver 120 is configured to scan (e.g., sequentially assert) the gate lines G [1] to G [N] to select pixels 110 to be driven or updated. In one implementation, the gate scan driver 120 is configured to assert the gate line G [i] when pixels 110 coupled to the gate line G [i] are driven or updated. The emission scan driver 130 is configured to scan the emission lines EM [1] to EM [N] to control light emission from the pixels 110 coupled to the emission lines EM [1] to EM [N].
More specifically, the PMOS transistors M1, M2, M3, and the OLED element D are coupled in series between a high-side power supply ELVDD and a low-side power supply ELVSS. The PMOS transistors M1, M2 and M3 form a path that provides a drive current depending on the voltage across the storage capacitor Cst. The gates of the PMOS transistors M1 and M3 are coupled to the emission line EM [i] and the gate of the PMOS transistor M2 is coupled to a storage node Nst. The OLED element D has an anode coupled to the drain of the PMOS transistor M3 and a cathode coupled to the low-side power supply ELVSS. The PMOS transistors M4, M5, and M6 each have a gate coupled to the gate line G [i]. The PMOS transistor M4 is coupled between the source line SL [i] and the source of the PMOS transistor M2. The PMOS transistor M5 is coupled between the storage node Nst and the drain of the PMOS transistor M2. The PMOS transistor M6 is coupled between the anode of the OLED element D and a node at which an initialization voltage VREEN is generated. The PMOS transistor M7 has a gate coupled to the gate line G [i−1], which is a gate line asserted during a horizontal period immediately preceding the horizontal period during which the gate line G [i] is asserted. It is noted that for i=1, the gate line G [0] may be a dummy gate line that is asserted during a horizontal period immediately preceding the horizontal period during which the gate line G [1] is asserted. The PMOS transistor M7 is coupled between the storage node Nst and the node at which the initialization voltage VREEN is generated.
In one implementation, a write operation is performed to update the pixel 110 with a drive voltage during a display update period. The write operation involves operating the gate lines G [i−1] and G [i] in a predetermined sequence in the state where the emission line EM [i] is deasserted and the drive voltage is applied to the source line SL [j]. This allows the drive voltage to be written into the storage capacitor Cst. As the emission line EM[i] is deasserted, the PMOS transistors M1 and M3 are opened (or turned off) and the OLED element D does not emit light during the write operation. When the emission line EM[i] is asserted after the write operation is completed, the PMOS transistors M1 and M3 are closed (or turned on) to provide the OLED element D with a drive current corresponding to the voltage across the storage capacitor Cst. The drive current allows the OLED element D to emit light at the luminance level corresponding to the data voltage.
The pixel 110 shown in
One approach to suppress or eliminate the charge leakage from the storage capacitor Cst of the pixel 110 is to drive the source line SL [j] to a “leakage suppression voltage” during the non-display update period. The leakage suppression voltage is a predetermined voltage in the allowed voltage range for the source line SL [j]. The voltage level of the “leakage suppression voltage” is adjusted to substantially maintain the voltage held across the storage capacitor Cst. In one implementation, the leakage suppression voltage may be set to a voltage level higher than the ELVDD level, where the ELVDD level is the voltage level of the high-side power supply voltage provided from the high-side power supply ELVDD to the respective pixels 110 of the display panel 100.
The present disclosure recognizes that since it would be advantageous for the leakage suppression voltage to be finely adjustable, one efficient way to drive the source lines SL [1] to SL [m] to the leakage suppression voltage is to use source amplifiers integrated in the display driver 200. However, using all of the source amplifiers to drive the source lines SL [1] to SL [m] to the leakage suppression voltage may consume considerable power. To reduce power consumption, embodiments of the present disclosure use some but not all of the source amplifiers integrated in the display driver 200 to provide the leakage suppression voltage to the source lines SL [1] to SL [m]. Presented below are embodiments of the present disclosure which suppress or eliminate charge leakage from storage capacitors in pixels with efficient source amplifier control to suppress power consumption. It should be noted that since the problem of charge leakage from storage capacitors of pixels may also be present in other pixel configurations, those skilled in the art would appreciate that the techniques disclosed in the present disclosure may be applied to display devices having different pixel configurations.
For any integer i between one and 2N, inclusive, the latch 210i, the DAC 220i, and the source amplifier 230i are collectively configured to generate and provide the data voltage to the source output S [i] based on the pixel data D [i]. More specifically, the latch 210i is configured to latch the pixel data D [i] from the data bus 240 and forward the pixel data D [i] to the DAC 220i. The DAC 220i is configured to receive a set of gamma voltages Vg [0] to Vg [M] and perform digital-to-analog conversion on the pixel data D [i] using the gamma voltages Vg [0] to Vg [M] to output a gamma voltage corresponding to the greylevel specified by the pixel data D [i]. In one implementation, the DAC 220i may be configured to select one of the gamma voltages Vg [0] to Vg [M] based on the greylevel specified by the pixel data D [i] and output the selected gamma voltage. The source amplifier 230i is configured to generate the data voltage corresponding to the pixel data D[i] based on the gamma voltage received from the DAC 220i. In one implementation, the source amplifier 230i may be configured to perform an impedance conversion on the received gamma voltage to generate the data voltage.
The switch circuitry 250 includes a first set of switches 2551 to 255N−1 and a second set of switches 255N+1 to 2552N−1. The switches 2551 to 255N−1 and 255N+1 to 2552N−1 may be collectively referred to as the switches 255 when the switches 2551 to 255N−1 and 255N+1 to 2552N−1 are not distinguished from one another. The switches 2551 to 255N−1 are coupled between the output of the source amplifier 2301 and the source outputs S [2] to S [N], respectively, while the switches 255N+1 to 2552N−1 are coupled between the output of the source amplifier 230N+1 and the source outputs S [N+2] to S [2N], respectively. While only six switches 255 are shown in
The register 260 is coupled to the latches 2101 to 2102N and configured to store and provide a “leakage suppression greylevel” GLLS to the latches 2101 to 2102N. The leakage suppression greylevel GLLS corresponds to the “leakage suppression voltage”, which means that each source amplifier 230 is configured to output the “leakage suppression voltage” when the leakage suppression greylevel GLLS is provided to the corresponding DAC 220. The latches 2101 to 2102N are configured to latch and provide the leakage suppression greylevel GLLS to the DACs 2201 to 2202N in response to an assertion of a latch control signal CTRL.
During the display update period of each vertical sync period, all the switches 255 are opened (which is indicated by “OFF” in
Referring back to
The source amplifiers 2301 and 230N+1 generate the leakage suppression voltage, denoted by “VLS” in
Further, the operation shown in
The operation shown in
The operation shown in
At step 702, a first source amplifier (e.g., the source amplifiers 2301 and 230x shown in
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Exemplary embodiments are described herein. Variations of those exemplary embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
