Edge column differential sensing systems and methods

Electronic displays, systems, and methods that perform display panel sensing are provided. An electronic device may include processing circuitry that generates image data based at least in part on display panel sensing feedback and an electronic display. The electronic display may display the image data on pixels coupled to one of several sense lines. There may be an odd number of sense lines with common electrical characteristics. The electronic display may obtain display panel sense feedback at least in part by differentially sensing each one of the sense lines with sense lines with common electrical characteristics with another one of the sense lines the common electrical characteristics.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Non-Provisional Patent Application of U.S. Provisional Patent Application No. 62/398,902, entitled “Edge Column Differential Sensing Systems and Methods”, filed Sep. 23, 2016, which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

This disclosure relates to display panel sensing to compensate for operational variations in the display panel and, more particularly, to reducing or eliminating common-mode display panel noise on display panels odd numbers of electrically similar columns.

Electronic displays are found in numerous electronic devices. As electronic displays gain higher resolutions that provide finer, more detailed images at higher dynamic ranges and a broader range of colors, the fidelity of the images becomes more valuable. To ensure the fidelity of the images displayed on an electronic display, display panel sensing may be used to sense operational variations in the pixels of an electronic display. These operational variations may be due to factors such as temperature or aging. Since factors such as temperature and aging tend to be non-uniform across the electronic display, a single uniform compensation may be insufficient to correct for image artifacts that would appear due to the operational variations of the electronic display. Display panel sensing may identify the variations across the display to enable more precise image compensation.

Some electronic displays use single-ended display panel sensing, where parameters of the electronic display are sensed in comparison to a fixed reference value. While single-ended display panel sensing may work for electronic displays that are very large and thus have a relatively low pixel density, using single-ended display panel sensing on electronic displays that are smaller with a greater pixel density may result in the detection of a substantial amount of noise. The amount of noise may be further increased by other electronic components that may be operating near the display, which may frequently occur in portable electronic devices, such as portable phones. Indeed, processors, cameras, wireless transmitters, and similar components could produce electromagnetic interference that interferes with display panel sensing.

SUMMARY

A number of systems and methods may be used to mitigate the effects of noise in display panel sensing. For example, differential sensing may be used to cancel out common mode noise of the display panel during sensing. Differential sensing involves performing display panel sensing not in comparison to a static reference, as is done in single-ended sensing, but instead in comparison to a dynamic reference that is exposed to similar electrical conditions as what is being tested. For example, to sense an operational parameter of a test pixel of an electronic display, the test pixel may be programmed with test data. The response by the test pixel to the test data may be sensed on a sense line (e.g., a data line) that is coupled to the test pixel. The sense line of the test pixel may be sensed in comparison to a sense line coupled to a reference pixel that was not programmed with the test data. The signal sensed from the reference pixel does not include any particular operational parameters relating to the reference pixel in particular, but rather contains common-noise that may be occurring on the sense lines of both the test pixel and the reference pixel. In other words, since the test pixel and the reference signal are both subject to the same system-level noise—such as electromagnetic interference from nearby components or external interference—differentially sensing the test pixel in comparison to the reference pixel results in at least some of the common-mode noise subtracted away from the signal of the test pixel.

It may be beneficial to perform differential sensing using two lines with similar electrical characteristics. For example, every other sense line may have electrical characteristics that are more similar than adjacent sense lines. An electronic display panel with an odd number of electrically similar sense lines may not perform differential sensing with every other sense line without having one remaining sense line that is left out.

Accordingly, this disclosure provides systems and methods to enable differential sensing of sense lines in a display panel even when the display panel contains odd numbers of electrically similar sense lines. In one example, some or all of the sense lines may be routed to sense amplifiers be differentially sensed with different sense lines at different points in time. These may be considered to be “dancing channels” that are not fixed in place, but rather may dance from sense amplifier to sense amplifier in a way that mitigates odd pairings.

DETAILED DESCRIPTION

Electronic displays are becoming ubiquitous in modern electronic devices. As electronic displays gain ever-higher resolutions and dynamic range capabilities, image quality has increasingly grown in value. In general, electronic displays contain numerous picture elements, or “pixels,” that are programmed with image data. Each pixel emits a particular amount of light based on the image data. By programming different pixels with different image data, graphical content including images, videos, and text can be displayed.

As mentioned above, display panel sensing allows for operational properties of pixels of an electronic display to be identified to improve the performance of the electronic display. For example, variations in temperature and pixel aging (among other things) across the electronic display cause pixels in different locations on the display to behave differently. Indeed, the same image data programmed on different pixels of the display could appear to be different due to the variations in temperature and pixel aging. Without appropriate compensation, these variations could produce undesirable visual artifacts. By sensing certain operational properties of the pixels, the image data may be adjusted to compensate for the operational variations across the display.

Display panel sensing involves programming certain pixels with test data and measuring a response by the pixels to the test data. The response by a pixel to test data may indicate how that pixel will perform when programmed with actual image data. In this disclosure, pixels that are currently being tested using the test data are referred to as “test pixels” and the response by the test pixels to the test data is referred to as a “test signal.” The test signal is sensed from a “sense line” of the electronic display and may be a voltage or a current, or both a voltage and a current. In some cases, the sense line may serve a dual purpose on the display panel. For example, data lines of the display that are used to program pixels of the display with image data may also serve as sense lines during display panel sensing.

To sense the test signal, it may be compared to some reference value. Although the reference value could be static—referred to as “single-ended” testing—using a static reference value may cause too much noise to remain in the test signal. Indeed, the test signal often contains both the signal of interest, which may be referred to as the “pixel operational parameter” or “electrical property” that is being sensed, as well as noise due to any number of electromagnetic interference sources near the sense line. Differential sensing (DS) may be used to cancel out common mode noise of the display panel during sensing.

Differential sensing involves performing display panel sensing not in comparison to a static reference, as is done in single-ended sensing, but instead in comparison to a dynamic reference. For example, to sense an operational parameter of a test pixel of an electronic display, the test pixel may be programmed with test data. The response by the test pixel to the test data may be sensed on a sense line (e.g., a data line) that is coupled to the test pixel. The sense line of the test pixel may be sensed in comparison to a sense line coupled to a reference pixel that was not programmed with the test data. The signal sensed from the reference pixel does not include any particular operational parameters relating to the reference pixel in particular, but rather contains common-noise that may be occurring on the sense lines of both the test pixel and the reference pixel. In other words, since the test pixel and the reference signal are both subject to the same system-level noise—such as electromagnetic interference from nearby components or external interference—differentially sensing the test pixel in comparison to the reference pixel results in at least some of the common-mode noise being subtracted away from the signal of the test pixel. The resulting differential sensing may be used in combination with other techniques, such as difference—differential sensing, correlated double sampling, and the like. A variety of these techniques are described in U.S. patent application Ser. No. 15/698,262 filed on Sep. 7, 2017 and entitled “Noise Mitigation For Display Panel Sensing”, which claims priority to U.S. patent application Ser. No. 62/397,845, filed Sep. 21, 2016 and entitled “Noise Mitigation for Display Panel Sensing,” which is incorporated by reference herein in its entirety for all purposes.

It may be beneficial to perform differential sensing using two lines with similar electrical characteristics. For example, every other sense line may have electrical characteristics that are more similar than adjacent sense lines. An electronic display panel with an odd number of electrically similar sense lines may not perform differential sensing with every other sense line without having one remaining sense line that is left out. Accordingly, this disclosure provides systems and methods to enable differential sensing of sense lines in a display panel even when the display panel contains odd numbers of electrically similar sense lines. In one example, some or all of the sense lines may be routed to sense amplifiers be differentially sensed with different sense lines at different points in time. These may be considered to be “dancing channels” that are not fixed in place, but rather may dance from sense amplifier to sense amplifier in a way that mitigates odd pairings.

With this in mind, a block diagram of an electronic device10is shown inFIG. 1that may perform differential sensing to reduce display panel sensing noise, even with a display panel having an odd number of electrically similar sense lines. As will be described in more detail below, the electronic device10may represent any suitable electronic device, such as a computer, a mobile phone, a portable media device, a tablet, a television, a virtual-reality headset, a vehicle dashboard, or the like. The electronic device10may represent, for example, a notebook computer10A as depicted inFIG. 2, a handheld device10B as depicted inFIG. 3, a handheld device10C as depicted inFIG. 4, a desktop computer10D as depicted inFIG. 5, a wearable electronic device10E as depicted inFIG. 6, or a similar device.

The electronic device10shown inFIG. 1may include, for example, a processor core complex12, a local memory14, a main memory storage device16, a display18, input structures22, an input/output (I/O) interface24, network interfaces26, and a power source28. The various functional blocks shown inFIG. 1may include hardware elements (including circuitry), software elements (including machine-executable instructions stored on a tangible, non-transitory medium, such as the local memory14or the main memory storage device16) or a combination of both hardware and software elements. It should be noted thatFIG. 1is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device10. Indeed, the various depicted components may be combined into fewer components or separated into additional components. For example, the local memory14and the main memory storage device16may be included in a single component.

The processor core complex12may carry out a variety of operations of the electronic device10, such as causing the electronic display18to perform display panel sensing and using the feedback to adjust image data for display on the electronic display18. The processor core complex12may include any suitable data processing circuitry to perform these operations, such as one or more microprocessors, one or more application specific processors (ASICs), or one or more programmable logic devices (PLDs). In some cases, the processor core complex12may execute programs or instructions (e.g., an operating system or application program) stored on a suitable article of manufacture, such as the local memory14and/or the main memory storage device16. In addition to instructions for the processor core complex12, the local memory14and/or the main memory storage device16may also store data to be processed by the processor core complex12. By way of example, the local memory14may include random access memory (RAM) and the main memory storage device16may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, or the like.

The electronic display18may display image frames that may contain a graphical user interface (GUI) for an operating system or an application interface, still images, and/or video content. The processor core complex12may supply at least some of the image frames. The electronic display18may be a self-emissive display, such as an organic light emitting diodes (OLED) display, or may be a liquid crystal display (LCD) illuminated by a backlight. In some embodiments, the electronic display18may include a touch screen, which may allow users to interact with a user interface of the electronic device10. The electronic display18may employ display panel sensing to identify operational variations of the electronic display18. This may allow the processor core complex12to adjust image data that is sent to the electronic display18to compensate for these variations, thereby improving the quality of the image frames appearing on the electronic display18.

The input structures22of the electronic device10may enable a user to interact with the electronic device10(e.g., pressing a button to increase or decrease a volume level). The I/O interface24may enable electronic device10to interface with various other electronic devices, as may the network interface26. The network interface26may include, for example, interfaces for a personal area network (PAN), such as a Bluetooth network, for a local area network (LAN) or wireless local area network (WLAN), such as an 802.11x Wi-Fi network, and/or for a wide area network (WAN), such as a cellular network. The network interface26may also include interfaces for, for example, broadband fixed wireless access networks (WiMAX), mobile broadband Wireless networks (mobile WiMAX), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T) and its extension DVB Handheld (DVB-H), ultra wideband (UWB), alternating current (AC) power lines, and so forth. The power source28may include any suitable source of power, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter.

In certain embodiments, the electronic device10may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device10in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device10, taking the form of a notebook computer10A, is illustrated inFIG. 2in accordance with one embodiment of the present disclosure. The depicted computer10A may include a housing or enclosure36, an electronic display18, input structures22, and ports of an I/O interface24. In one embodiment, the input structures22(such as a keyboard and/or touchpad) may be used to interact with the computer10A, such as to start, control, or operate a GUI or applications running on computer10A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on the electronic display18.

FIG. 3depicts a front view of a handheld device10B, which represents one embodiment of the electronic device10. The handheld device10B may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device10B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. The handheld device10B may include an enclosure36to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure36may surround the electronic display18. The I/O interfaces24may open through the enclosure36and may include, for example, an I/O port for a hard wired connection for charging and/or content manipulation using a standard connector and protocol, such as the Lightning connector provided by Apple Inc., a universal service bus (USB), or other similar connector and protocol.

User input structures22, in combination with the electronic display18, may allow a user to control the handheld device10B. For example, the input structures22may activate or deactivate the handheld device10B, navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device10B. Other input structures22may provide volume control, or may toggle between vibrate and ring modes. The input structures22may also include a microphone may obtain a user's voice for various voice-related features, and a speaker may enable audio playback and/or certain phone capabilities. The input structures22may also include a headphone input may provide a connection to external speakers and/or headphones.

FIG. 4depicts a front view of another handheld device10C, which represents another embodiment of the electronic device10. The handheld device10C may represent, for example, a tablet computer or portable computing device. By way of example, the handheld device10C may be a tablet-sized embodiment of the electronic device10, which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif.

Turning toFIG. 5, a computer10D may represent another embodiment of the electronic device10ofFIG. 1. The computer10D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer10D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer10D may also represent a personal computer (PC) by another manufacturer. A similar enclosure36may be provided to protect and enclose internal components of the computer10D such as the electronic display18. In certain embodiments, a user of the computer10D may interact with the computer10D using various peripheral input devices, such as the keyboard22A or mouse22B (e.g., input structures22), which may connect to the computer10D.

Similarly,FIG. 6depicts a wearable electronic device10E representing another embodiment of the electronic device10ofFIG. 1that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device10E, which may include a wristband43, may be an Apple Watch® by Apple, Inc. However, in other embodiments, the wearable electronic device10E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The electronic display18of the wearable electronic device10E may include a touch screen display18(e.g., LCD, OLED display, active-matrix organic light emitting diode (AMOLED) display, and so forth), as well as input structures22, which may allow users to interact with a user interface of the wearable electronic device10E.

As shown inFIG. 7, in the various embodiments of the electronic device10, the processor core complex12may perform image data generation and processing50to generate image data52for display by the electronic display18. The image data generation and processing50of the processor core complex12is meant to represent the various circuitry and processing that may be employed by the core processor12to generate the image data52and control the electronic display18. Since this may include compensating the image data52based on operational variations of the electronic display18, the processor core complex12may provide sense control signals54to cause the electronic display18to perform display panel sensing to generate display sense feedback56. The display sense feedback56represents digital information relating to the operational variations of the electronic display18. The display sense feedback56may take any suitable form, and may be converted by the image data generation and processing50into a compensation value that, when applied to the image data52, appropriately compensates the image data52for the conditions of the electronic display18. This results in greater fidelity of the image data52, reducing or eliminating visual artifacts that would otherwise occur due to the operational variations of the electronic display18.

The electronic display18includes an active area64with an array of pixels66. The pixels66are schematically shown distributed substantially equally apart and of the same size, but in an actual implementation, pixels of different colors may have different spatial relationships to one another and may have different sizes. In one example, the pixels66may take a red-green-blue (RGB) format with red, green, and blue pixels, and in another example, the pixels66may take a red-green-blue-green (RGBG) format in a diamond pattern. The pixels66are controlled by a driver integrated circuit68, which may be a single module or may be made up of separate modules, such as a column driver integrated circuit68A and a row driver integrated circuit68B. The driver integrated circuit68may send signals across gate lines70to cause a row of pixels66to become activated and programmable, at which point the driver integrated circuit68(e.g.,68A) may transmit image data signals across data lines72to program the pixels66to display a particular gray level. By supplying different pixels66of different colors with image data to display different gray levels or different brightness, full-color images may be programmed into the pixels66. The image data may be driven to an active row of pixel66via source drivers74, which are also sometimes referred to as column drivers.

As mentioned above, the pixels66may be arranged in any suitable layout with the pixels66having various colors and/or shapes. For example, the pixels66may appear in alternating red, green, and blue in some embodiments, but also may take other arrangements. The other arrangements may include, for example, a red-green-blue-white (RGBW) layout or a diamond pattern layout in which one column of pixels alternates between red and blue and an adjacent column of pixels are green. Regardless of the particular arrangement and layout of the pixels66, each pixel66may be sensitive to changes on the active area of64of the electronic display18, such as variations and temperature of the active area64, as well as the overall age of the pixel66. Indeed, when each pixel66is a light emitting diode (LED), it may gradually emit less light over time. This effect is referred to as aging, and takes place over a slower time period than the effect of temperature on the pixel66of the electronic display18.

Display panel sensing may be used to obtain the display sense feedback56, which may enable the processor core complex12to generate compensated image data52to negate the effects of temperature, aging, and other variations of the active area64. The driver integrated circuit68(e.g.,68A) may include a sensing analog front end (AFE)76to perform analog sensing of the response of pixels66to test data. The analog signal may be digitized by sensing analog-to-digital conversion circuitry (ADC)78.

For example, to perform display panel sensing, the electronic display18may program one of the pixels66with test data. The sensing analog front end76then senses a sense line80of connected to the pixel66that is being tested. Here, the data lines72are shown to act as the sense lines80of the electronic display18. In other embodiments, however, the display active area64may include other dedicated sense lines80or other lines of the display may be used as sense lines80instead of the data lines72. Other pixels66that have not been programmed with test data may be sensed at the same time a pixel that has been programmed with test data. Indeed, as will be discussed below, by sensing a reference signal on a sense line80when a pixel on that sense line80has not been programmed with test data, a common-mode noise reference value may be obtained. This reference signal can be removed from the signal from the test pixel that has been programmed with test data to reduce or eliminate common mode noise.

The analog signal may be digitized by the sensing analog-to-digital conversion circuitry78. The sensing analog front end76and the sensing analog-to-digital conversion circuitry78may operate, in effect, as a single unit. The driver integrated circuit68(e.g.,68A) may also perform additional digital operations to generate the display feedback56, such as digital filtering, adding, or subtracting, to generate the display feedback56, or such processing may be performed by the processor core complex12.

FIG. 8illustrates a single-ended approach to display panel sensing. Namely, the sensing analog front end76and the sensing analog-to-digital conversion circuitry78may be represented schematically by sense amplifiers90that differentially sense a signal from the sense lines80(here, the data lines72) in comparison to a static reference signal92and output a digital value. It should be appreciated that, inFIG. 8as well as other figures of this disclosure, the sense amplifiers90are intended to represent both analog amplification circuitry and/or the sense analog to digital conversion (ADC) circuitry78. Whether the sense amplifiers90represent analog or digital circuitry, or both, may be understood through the context of other circuitry in each figure. A digital filter94may be used to digitally process the resulting digital signals obtained by the sense amplifiers90.

The single-ended display panel sensing shown inFIG. 8may generally follow a process110shown inFIG. 9. Namely, a pixel66may be driven with test data (referred to as a “test pixel”) (block112). Any suitable pixel66may be selected to be driven with the test data. In one example, all of the pixels66of a particular row are activated and driven with test pixel data. After the test pixel has been driven with the test data, the differential amplifiers90may sense the test pixels differentially in comparison to the static reference signal92to obtain sensed test signal data (block114). The sensed test pixel data may be digitized (block116) to be filtered by the digital filter94or for analysis by the processor core complex12.

Although the single-ended approach ofFIG. 8may operate to efficiently obtain sensed test pixel data, the sense lines80of the active area64(e.g., the data lines72) may be susceptible to noise from the other components of the electronic device10or other electrical signals in the vicinity of the electronic device10, such as radio signals, electromagnetic interference from data processing, and so forth. This may increase an amount of noise in the sensed signal, which may make it difficult to amplify the sensed signal within a specified dynamic range. An example is shown by a plot120ofFIG. 10. The plot120compares the detected signal of the sensed pixel data (ordinate122) over the sensing time (abscissa124). Here, a specified dynamic range126is dominated not by a desired test pixel signal128, but rather by leakage noise130. To cancel out some of the leakage noise130, and therefore improve the signal-to-noise ratio, an approach other than, or in addition to, a single-ended sensing approach may be used. For example, the electronic display18may perform differential sensing to cancel out certain common mode noise.

Differential sensing involves sensing a test pixel that has been driven with test data in comparison to a reference pixel that has not been applied with test data. By doing so, common-mode noise that is present on the sense lines80of both the test pixel and the reference pixel may be excluded.FIGS. 11-15describe a few differential sensing approaches that may be used by the electronic display18. InFIG. 11, the electronic display18includes sense amplifiers90that are connected to differentially sense two sense lines80. In the example shown inFIG. 11, columns132and134can be differentially sensed in relation to one another, columns136and138can be differentially sensed in relation to one another, columns140and142can be differentially sensed in relation to one another, and columns144and146can be differentially sensed in relation to one another.

As shown by a process150ofFIG. 12, differential sensing may involve driving a test pixel66with test data (block152). The test pixel66may be sensed differentially in relation to a reference pixel or reference sense line80that was not driven with test data (block154). For example, a test pixel66may be the first pixel66in the first column132, and the reference pixel66may be the first pixel66of the second column134. By sensing the test pixel66in this way, the sense amplifier90may obtain test pixel66data with reduced common-mode noise. The sensed test pixel66data may be digitized (block156) for further filtering or processing.

As a result, the signal-to-noise ratio of the sensed test pixel66data may be substantially better using the differential sensing approach than using a single-ended approach. Indeed, this is shown in a plot160ofFIG. 13, which compares a test signal value (ordinate122) in comparison to a sensing time (abscissa124). In the plot160, even with the same dynamic range specification126as shown in the plot120ofFIG. 10, the desired test pixel signal128may be much higher than the leakage noise130. This is because the common-mode noise that is common to the sense lines80of both the test pixel66and the reference pixel66may be subtracted when the differential amplifier90compares the test signal to the reference signal. This also provides an opportunity to increase the gain of the signal128by providing additional headroom162between the desired test pixel signal128and the dynamic range specification126.

Differential sensing may take place by comparing a test pixel66from one column with a reference pixel66from any other suitable column. For example, as shown inFIG. 14, the sense amplifiers90may differentially sense pixels66in relation to columns with similar electrical characteristics. In this example, even columns have electrical characteristics more similar to other even columns, and odd columns have electrical characteristics more similar to other odd columns. Here, for instance, the column132may be differentially sensed with column136, the column140may be differentially sensed with column144, the column134may be differentially sensed with column138, and column142may be differentially sensed with column146. This approach may improve the signal quality when the electrical characteristics of the sense lines80of even columns are more similar to those of sense lines80of other even columns, and the electrical characteristics of the sense lines80of odd columns are more similar to those of sense lines80of other odd columns. This may be the case for an RGBG configuration, in which even columns have red or blue pixels and odd columns have green pixels and, as a result, the electrical characteristics of the even columns may differ somewhat from the electrical characteristics of the odd columns. In other examples, the sense amplifiers90may differentially sense test pixels66in comparison to reference pixels66from every third column or, as shown inFIG. 15, every fourth column. It should be appreciated that the configuration ofFIG. 15may be particularly useful when every fourth column is more electrically similar to one another than to other columns.

One reason different electrical characteristics could occur on the sense lines80of different columns of pixels66is illustrated byFIGS. 16 and 17. As shown inFIG. 16, when the sense lines80are represented by the data lines72, a first data line72A and a second data line72B (which may be associated with different colors of pixels or different pixel arrangements) may share the same capacitance C1with another conductive line168in the active area64of the electronic display18because the other line168is aligned equally between the data lines72A and72B. The other line168may be any other conductive line, such as a power supply line like a high or low voltage rail for electroluminance of the pixels166(e.g., VDDEL or VSSEL). Here, the data lines72A and72B appear in one layer170, while the conductive line168appears in a different layer172. Being in two separate layers170and172, the data lines72A and72B may be fabricated at a different step in the manufacturing process from the conductive line168. Thus, it is possible for the layers to be misaligned when the electronic display18is fabricated.

Such layer misalignment is shown inFIG. 17. In the example ofFIG. 17, the conductive line168is shown to be farther from the first data line72A and closer to the second data line72B. This produces an unequal capacitance between the first data line72A and the conductive line168in comparison to the second data line72B and the conductive line168. These are shown as a capacitance C on the data line72A and a capacitance C+ΔC on the data line72B.

These different capacitances on the data lines72A compared to72B suggest that differential sensing may be enhanced by differentially sensing a data line72A with another data line72A, and sensing a data line72B with another data line72B. When there are an even number of electrically similar data lines72A and an even number of electrically similar data lines72B, differential sensing can take place in the manner described above with reference toFIG. 14. An odd number of electrically similar data lines72A or an odd numbers of electrically similar data lines72B, however, may introduce challenges. Indeed, when each electrically similar data line72A is differentially sensed with one other electrically similar data line72A, that would leave one remaining data line72A that is not differentially sensed with another electrically similar data line72A. The same would be true for the electrically similar data lines72B.

A few approaches to differential sensing that can accommodate an odd number of electrically similar data lines72A or72B are described with reference to the subsequent drawings. Namely, as shown inFIG. 18, there may be an odd number of groups of columns132and134that are coupled respectively to data lines72A and72B. In this example, there are N groups of columns132and134, where N is an odd number. As a result, there may be one remaining group of columns132and134on the active area64that are not able to be sensed differentially with another respective column132or134on the active area64. Accordingly, the approach ofFIG. 18adds dummy columns180that includes additional dummy circuitry that will not be used to actively display image data (e.g., may be disposed outside of a portion of the active area64that will be visible). The dummy columns180include a dummy data line72A that can be differentially sensed with the last data line72A of the Nth column, and a dummy data line72B that can be differentially sensed with the data line72B of the Nth column. In this way, differential sensing may be used, even for an active area64that includes an odd number of electrically similar columns for display.

Another example is shown inFIG. 19, which does not include any dummy data lines72A or72B, but rather differentially senses the final columns132and134of the Nth column together. Although the data lines72A and72B of the Nth group of columns are not entirely electrically similar, this may at least permit differential sensing to occur when the number of electrically similar columns of the active area64is an odd number.

A variation of the circuitry ofFIG. 19may involve maintaining a common differential sensing structure, but may use a different form of sensing routing, as shown inFIG. 20. Here, electrical variations in the driver integrated circuit68in the form of differential sensing used for groups of columns1,2, and so forth may be involve the same additional circuitry190for Nth group of columns. Additionally or alternatively, load matching may be applied to enable differential sensing for an odd number N groups of columns, as shown inFIG. 21. Indeed, inFIG. 21, the driver integrated circuit68may include differential sensing circuitry, such as the sense amplifiers90, coupled to load matching circuitry200. The load matching circuitry200may apply a load to have roughly the same electrical characteristics as the column72A when the column72A of the Nth group of columns is differentially sensed, and to apply a capacitance of roughly the same capacitance as the data line72B when the data line72B of the Nth group of columns is differentially sensed.

Another manner of differentially sensing an odd number of electrically similar columns is shown inFIG. 22. InFIG. 22, the active area64is connected to the display driver integrated circuit68through routing circuitry210. The routing circuitry210may be a chip-on-flex (COF) interconnection, or any other suitable routing circuitry to connect the driver integrated circuit68to the active area64of the electronic display18. The sensing circuitry of the driver integrated circuit68may be connected to a first number of fixed channels212and a second number of dancing channels214.

When the active area64of the electronic display18includes an even number of electrically similar columns, such as an even number of data lines72A and even number of data lines72B, the routing circuitry210may route all of the columns to the main fixed channels212. When the active area64of the electronic display18includes an odd number N of the data lines72A or72B, the routing circuitry210may route at least three of each of the data lines72A and at least three of the72B to the dancing channels214. In this example, the electronic display18includes an active area64with in N odd groups of columns, each of which includes two data lines72A and72B that are more electrically similarly to other respective data lines72A and72B than to each other (i.e., a data line72A may be more electrically similar to another data line72A, and a data line72B may be more electrically similar to another data line72B). For ease of explanation, only sense amplifiers90A,90B,90C, and90D that are used to sense the data lines72A are shown. However, it should be understood that similar circuitry may be used to differentially sense the other electrically similar data lines72B. Here, the last three groups of columns N, N-1, and N-2are routed to the dancing channels214.

The dancing channels214allow differential sensing of the odd number of electrically similar using switches216and218. The switches216and218may be used to selectively route the data line72A from the N-1group of columns to the sense amplifier90C for comparison with (1) the data line72A from the N-2group of columns or (2) the sense amplifier90D for comparison with the data line72A from the N group of columns. Dummy switches220and222may be provided for load-matching purposes to offset the loading effects of the switches216and218.

Thus, the dancing channels214shown inFIG. 22may allow each of the odd number N of electrically similar channels72A to be differentially sensed with another electrically similar channel72A, as described by a flowchart230shown inFIG. 23. Namely, at one point in time, the data lines72A from column N may be differentially sensed against the data line72A from column N-1using first sensing circuitry (e.g., sense amplifier90D) (block232). The data line72A from column N-1may be differentially tested against the data line72A of column N-2using second sensing circuitry (e.g., sense amplifier90C) (block234).

The dancing channels shown inFIG. 22may be located on a display driver channel configuration240as shown inFIG. 24. InFIG. 24, active east channels242are equal in number to N/2+2 total channels, while active west channels244encompass N/2 channels. A space of unused channels246may be included when fewer total channels are used than all of the channels that may be available on the driver integrated circuit. Channels248represent the dancing channels214. Here, the dancing channels248may appear as part of both the east channels242and the west channels244to maintain loading similarity.

FIG. 25represents an example of dancing channels that may occur over a wider portion of the active area64of the electronic display18. Indeed, the dancing channels may have access to data lines72from the entire active area64. Furthermore, while the example shown inFIG. 25relates to voltage sensing, it should be appreciated that, in other examples, current sensing may be used instead. The circuitry ofFIG. 25includes the sensing circuitry of the driver integrated circuit68, which includes a number of differential sense amplifiers90that are coupled to selection circuitry260. The selection circuitry260may be part of the driver integrated circuit68, or may be located on the active area64, or may be located on routing circuitry between the driver integrated circuit68and the active area64, or may be distributed across these locations. The selection circuitry260enables electrically similar data lines72A to be sensed in combination with neighboring electrically similar data lines72A at different points in time. For example, at one time, data lines72A from columns N and N-1may be differentially sensed, data lines72A from columns N-2and N-3may be sensed. At another time, data lines from columns N-1and N-2may be differentially sensed, and the data lines72A from columns N-3and N-4may be differentially sensed, and so forth.

An example of dancing channels that use current sensing is shown inFIG. 26. In the example ofFIG. 26, electrically similar data lines72A from 5 columns N, N-1, N-2, N-3, and N-4are shown. It should be appreciated that any suitable number of data lines72A may be used and this pattern may repeat any suitable number of times as desired. A current source270is applied to sense transistors272that sense the signal on the electrically similar data lines72A. A variable amount of the current signal from the current source270passes through the sense transistors272onto selection circuitry274. The selection circuitry274may be used to select which of the electrically similar data lines72A are differentially sensed. Indeed, in the circuitry ofFIG. 26, the selection circuitry274may allow:a. the data line72A from the column N to be differentially sensed with either of the data lines72A from columns N-1or N-2;b. the data line72A from the column N-1to be differentially sensed with either of the data lines72A from columns N or N-2; andc. the data line72A from the column N-2to be differentially sensed with either of the data lines72A from columns N or N-1or from columns N-3or N-4.

The pattern shown inFIG. 26may continue across channels from the entire display active area64.

Dancing channels shown inFIG. 27are implemented with slightly different circuitry. In this example, each data line72A from a number of columns N-2, N-1, N are coupled into sensing circuitry that uses current sensing based on one current source326, and data lines72A from columns N, N+1, N+2, are coupled into another current source326. Sense transistors328may differentially sense the signals of two of the data lines72A as routed by the selection circuitry ofFIG. 27, which will be described further below, based on the current source326and an integration capacitance CINT. For instance, switches330,332, and334allow the data line72A of column N to be differentially sensed with the data line72A of column N-1or the data line72A of column N+1, as well as to pass further signals down to following stages of differential sensing with other columns beyond those shown inFIG. 27. Switches338,340,342, and344may operate as either dummy switches or to pass signals down to the following stages.

FIG. 28represents an example of dancing channels as applied shown inFIG. 27are implemented to the last, odd group of electrically similar columns. InFIG. 28, P1represents a first type of pixels that may be present on the data line72A (e.g., red pixels and blue pixels), and P2represents pixels that may be found on the data line72B (e.g., green pixels). A final sense amplifier90may selectively differentially sense different electrically similar data lines72using switches360,362,364, and366. The last electrically similar data line72A may be differentially sensed with the second-to-last data line72A by opening the switches360and364and closing the switches362and366The last electrically similar data line72B may be differentially sensed with the second-to-last data line72B by closing the switches360and364and opening the switches362and366.

An example of dancing channels shown inFIG. 29may enable an even greater number of differential sensing patterns. Here, differential sense amplifiers90are coupled to selection circuitry370, each of which has four inputs. In the example ofFIG. 29, the four inputs include data lines72from with both electrically similar and electrically dissimilar characteristics. For example, in the example ofFIG. 29, a first selection circuitry270may selectively allow a signal to be sensed from a first column of a pixel of a first type (P11) (e.g., alternating rows of red pixels and blue pixels), a second column of a pixel of a second type (P22) (e.g., rows of second green pixels), a third column of a pixel of the first type (P13) (e.g., alternating rows of red pixels and blue pixels), and a third column of a pixel of a second type (P23) (e.g., rows of first green pixels), and a second selection circuitry270may selectively allow a signal to be sensed from a first column of a pixel of the second type (P21) (e.g., rows of first green pixels), a second column of a pixel of the first type (P12) (e.g., alternating rows of blue and red pixels), a fourth column of a pixel of the second type (P24) (e.g., rows of the second green pixels), and a fourth column of a pixel of the first type (P14) (e.g., alternating rows of blue and red pixels), which may be done for a red-green-blue-green (RGBG) pixel arrangement on the active area64of the electronic display18. Similar arrangements are coupled to other sense amplifiers90. In effect, this may allow a given column of pixels to be sensed with a wide variety of other columns of pixels as desired. It should be appreciated that the arrangement shown inFIG. 29is provided by way of example, and that many other arrangements may be used. Indeed, in another example, each selection circuitry270may include three inputs, and fewer columns of pixels may be differentially sensed in relation to each other, or may include more than four inputs, and more columns of pixels may be differentially sensed in relation to each other.

The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. For example, while differential sensing has been described with reference to sense lines that are also data lines having electrically similar characteristics, it should be appreciated that the sense lines may be any other conductive lines on the electronic display having electrically similar characteristics. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.