Display architecture with reduced number of data line connections

Pixel arrangements for full-color displays are provided in which the number of data lines per pixel is less than the number of colors of sub-pixels within each pixel. RGB1B2-type arrangements are provided in which activation of one blue sub-pixel deactivates or prevents activation of the other.

FIELD

The present invention relates to structures and components suitable for use in organic light emitting diodes (OLEDs) and devices including the same.

BACKGROUND

As used herein, a “red” sub-pixel, layer, material, region, or device refers to one that emits light in the range of about 580-700 nm; a “green” sub-pixel layer, material, region, or device refers to one that has an emission spectrum with a peak wavelength in the range of about 500-600 nm; a “blue” sub-pixel layer, material, or device refers to one that has an emission spectrum with a peak wavelength in the range of about 400-500 nm; and a “yellow” sub-pixel, layer, material, region, or device refers to one that has an emission spectrum with a peak wavelength in the range of about 540-600 nm. In some arrangements, separate regions, layers, materials, regions, or devices may provide separate “deep blue” and a “light blue” light. As used herein, in arrangements that provide separate “light blue” and “deep blue”, the “deep blue” component refers to one having a peak emission wavelength that is at least about 4 nm less than the peak emission wavelength of the “light blue” component. Typically, a “light blue” component has a peak emission wavelength in the range of about 465-500 nm, and a “deep blue” component has a peak emission wavelength in the range of about 400-475 nm, though these ranges may vary for some configurations. Similarly, a color altering layer refers to a layer that converts or modifies another color of light to light having a wavelength as specified for that color. For example, a “red” color filter refers to a filter that results in light having a wavelength in the range of about 580-700 nm. In general there are two classes of color altering layers: color filters that modify a spectrum by removing unwanted wavelengths of light, and color changing layers that convert photons of higher energy to lower energy.

As used herein, a “full-color” device, pixel, or other component refers to one that includes red, green, and blue components, and which is capable of being configured to emit a range of light across the visible spectrum. A “full-color” device may include multiple sub-pixels, each of which may be configured to emit one or more colors of light. For example, a full-color pixel may include one or more red, green, blue, and/or yellow sub-pixels, each of which emits the corresponding light. For example, a red sub-pixel may emit red light as previously defined, which, in conjunction with the other sub-pixels, allows the pixel to be a full-color pixel. Full-color pixels or other components typically also may be capable of emitting white light, such as by activating multiple colors of sub-pixels concurrently. In some cases, a full-color pixel also may include a white or other multi-color sub-pixel or similar component.

In contrast to a full-color device, pixel, or other component, a “single-color” sub-pixel or other component does not include multiple components of different colors and typically emits light only within a single color range. For example, a red single-color sub-pixel typically emits light within the red visible spectrum, i.e., 580-700 nm. A single-color sub-pixel will emit all, or essentially all, visible light emitted by the sub-pixel within the associated spectrum range. That is, while a very small amount of energy emitted by a single-color sub-pixel within the visible spectrum may fall outside the associated color range, it will be a sufficiently small amount that the difference in color is not noticeable to the human eye.

SUMMARY

According to an embodiment, an organic light emitting diode/device (OLED) is also provided. The OLED can include an anode, a cathode, and an organic layer, disposed between the anode and the cathode. According to an embodiment, the organic light emitting device is incorporated into one or more device selected from a consumer product, an electronic component module, and/or a lighting panel.

DETAILED DESCRIPTION

In some embodiments disclosed herein, emissive layers or materials, such as emissive layer135and emissive layer220shown inFIGS. 1-2, respectively, may include quantum dots. An “emissive layer” or “emissive material” as disclosed herein may include an organic emissive material and/or an emissive material that contains quantum dots or equivalent structures, unless indicated to the contrary explicitly or by context according to the understanding of one of skill in the art. Such an emissive layer may include only a quantum dot material which converts light emitted by a separate emissive material or other emitter, or it may also include the separate emissive material or other emitter, or it may emit light itself directly from the application of an electric current. Similarly, a color altering layer, color filter, upconversion, or downconversion layer or structure may include a material containing quantum dots, though such layer may not be considered an “emissive layer” as disclosed herein. In general, an “emissive layer” or material is one that emits an initial light, which may be altered by another layer such as a color filter or other color altering layer that does not itself emit an initial light within the device, but may re-emit altered light of a different spectra content based upon initial light emitted by the emissive layer.

In some embodiments of the emissive region, the emissive region further comprises a host.

In some embodiments, the compound can be an emissive dopant. In some embodiments, the compound can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence), triplet-triplet annihilation, or combinations of these processes.

The organic layer can also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the hosts used may be a) bipolar, b) electron transporting, c) hole transporting or d) wide band gap materials that play little role in charge transport. In some embodiments, the host can include a metal complex. The host can be an inorganic compound.

Combination with Other Materials

Various materials may be used for the various emissive and non-emissive layers and arrangements disclosed herein. Examples of suitable materials are disclosed in U.S. Patent Application Publication No. 2017/0229663, which is incorporated by reference in its entirety.

A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material.

An electron transport layer (ETL) may include a material capable of transporting electrons. The electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

Charge Generation Layer (CGL)

OLED devices as disclosed herein often are incorporated into other devices, such as display panels, portable electronics, and the like. Such devices typically include an array of full-color pixels, each of which is formed by a set of sub-pixels. It has been found that there are benefits to using pixel arrangements in which each pixel uses two single-color blue sub-pixels, light blue and deep blue, which may be referred to as a RGB1B2 or B1B2 architecture. For example, an architecture that includes light and deep blue sub-pixels may be used to enable a longer-lifetime phosphorescent light blue sub-pixel to be used in a display instead of, or in conjunction with deep blue sub-pixels, which typically have a lower average lifetime, thereby improving the efficiency of the device. Most images have little or no deep blue color content, so the light blue sub-pixel can be used to render any blue color in a displayed image other than images where a deep blue is explicitly required. It has also been found that the use of a B1B2 pixel arrangement may have health benefits due to a reduced amount of deep blue light emission.

Unfortunately many B1B2 architectures used in the past came with increased cost and complexity of the layout and drive circuitry, making it more costly to implement than a conventional RGB display. In contrast, embodiments disclosed herein provide methods and devices that implement B1B2-type OLED displays that may use only 3 OLED depositions, have little or no reduction in sub-pixel fill factors, and/or no more data or scan lines than would be required for a conventional RGB display, while achieving an improved lifetime with reduced manufacturing cost and complexity. Embodiments disclosed herein may achieve these improved results, for example, because at any given time all pixels may use either a deep blue or a light blue color, but the device may be restricted such that both blue colors are never used at the same time in the same pixel.

FIG. 3Ashows an example layout of a layout for a RGB1B2 display according to embodiments disclosed herein, where each deep blue (B2) sub-pixel may be shared by four pixels. The arrangement includes multiple full-color pixels such as pixels301,302. Full-color pixel301includes single-color sub-pixels310,320,330, which emit red, green, and light blue, respectively, and350, which emits deep blue. An adjacent pixel302includes a similar arrangement of single-color sub-pixels311,321,332,350. Notably, the deep blue sub-pixel350is “shared” by both pixels301,302as well as two pixels shown below the pixels301,302. As used herein, a single sub-pixel may be “shared” among multiple full-color pixels when it is physically and electrically arranged such that it can be used by one, some, or all of the pixels that share it to generate the color(s) as indicated by a data signal that drives each of the multiple pixels. In this arrangement, each deep blue sub-pixel350,351may be shared by up to four full-color pixels as shown. Sharing deep blue sub-pixels by more than one pixel allows for a smaller increase in the number of data lines needed to support a four sub-pixel per pixel architecture compared to conventional architectures, and also allows the deep blue sub-pixel to have a larger fill-factor, thereby improving its lifetime. This deep blue sub-pixel sharing is facilitated by the human eye only having a lower spatial resolution to deep blue than other colors. That is, it may be especially advantageous to use arrangements that allow for deep blue sub-pixel sharing compared to other colors because any resulting potential change may be less visible to the human eye and, in some cases, may be entirely undetectable.

FIG. 3Ashows an embodiment in which a deep blue sub-pixel may be shared by up to four pixels. Other embodiments may be used. For example,FIG. 3Bshows a similar arrangement in which each deep blue sub-pixel353is shared among two adjacent full-color pixels305,306. Each pixel305,306also includes red, green, and light blue sub-pixels310,320,330as previously disclosed. In arrangements such as shown inFIGS. 3A and 3B, the sub-pixel pattern may be repeated across any number of rows and columns or other repeated arrangements to achieve a desired panel size.

As previously noted, embodiments disclosed herein may allow for efficient fabrication and use of B1B2-type architectures by using control circuits that require a relatively low number of data lines, and/or which prevent both blue sub-pixels from being activated concurrently.FIG. 4shows an example control circuit for driving two blue sub-pixels in an RGB1B2 device according to an embodiment. In this arrangement, only a single data line and a single sub-pixel driving circuit is used for both the B1 and B2 sub-pixels. This allows for activation of one blue sub-pixel, such as the deep blue B2 sub-pixel, to deactivate or prevent activation of the other, such as the light blue B1 sub-pixel. In this example, the B2 Vdd line is switchable such that when the B2 sub-pixel is energized, the B1 sub-pixel is switched to an inactive state. This arrangement may use an additional switched (frame rate) power supply line for B1 that will be enabled when any pixel connected to that line needs the specific color provided by the B2 deep blue sub-pixel—“deep blue data line”—which may be evaluated frame by frame.

A single sub-pixel drive circuit410may be shared by the B1 and B2 OLEDs, i.e., the circuit410may control each of the B1 and B2 sub-pixels depending upon which is active. During use of such a control circuit, the deep blue B2 sub-pixel may be activated when it is required based upon the color data provided on the single data line to achieve a specified blue color. As previously described, this deactivates the light blue B1 sub-pixel so that only one blue sub-pixel is active at any time. The light blue B1 sub-pixel is activated for any blue emission needed by the full-color pixel or pixels of which the B1 and B2 sub-pixels are a part that does not require the specific emission provided by the deep blue B2 sub-pixel. A light blue sub-pixel may be used in conjunction with one or more color-altering components to achieve a wider range of blue emission, further decreasing the need for activation of the deep blue sub-pixel. Examples of suitable color altering components include color filters, color altering layers, up-conversion layers, down-conversion layers, and the like, including quantum dot layers, microcavities, doped organic layers, and the like. Such color-altering layers also may be used in conjunction with one or more other sub-pixels in a display, such as to increase the color range of a particular sub-pixel.

The sub-pixel driving circuit410may be, for example, a simple thin film transistor (TFT) which has a source line connected to the data line, the gate line connected to the scan line, and the drain line connected to transistors T1and T2as shown. In embodiments that employ pixel compensation, this driving circuit would may be a multi-TFT driving circuit. In this case T1and T2represent pass transistors that isolate the gates of the two driver TFTs so that when the light blue sub-pixel B1 driver TFT is turned off by activating Vdd of the deep blue B2 sub-pixel, it does not also turn off the driver TFT for the B2 sub-pixel. T3and T4connect the gate and source of the B1 driver TFT when Vdd B2 is activated, thereby shutting off the B1 sub-pixel when the B2 sub-pixel is energized. This connection of the B1 driver TFT gate to source can only occur after the sub-pixel driving circuit has placed the appropriate grey scale drive signal on the gate of the B2 driver TFT. This may be enabled by using the subsequent scan line voltage to activate the T3and T4path. This ensures that turning off B1 does not impact B2. Other arrangements may be used to reduce the number of data lines needed in comparison to the number of colors of sub-pixels in the pixel, and other components of the control circuitry may be the same as used in RGB1B2 arrangements or other B1B2-type architectures, including other control circuitry and scan line arrangements. That is, embodiments disclosed herein may not require any change in the scan line driver from a conventional arrangement, so such implementations may use standard data and scan line drivers and may only require additional switched power supplies for Vdd as shown.

In other arrangements, separate driving circuits may be used for each sub-pixel even where only a single data line is used.FIG. 5shows an example circuit arrangement that includes separate sub-pixel driving circuits. In this arrangement, a first sub-pixel drive circuit510drives the light blue B1 sub-pixel, and a second separate sub-pixel drive circuit520drives the deep blue B2 sub-pixel. Similarly to the arrangement shown inFIG. 4, a single data line is used for both blue sub-pixels and when the deep blue B2 sub-pixel is active, the light blue B1 sub-pixel is deactivated or prevented from activation. For example, the B2 Vdd may be switchable such that when the B2 sub-pixel is energized, the B1 sub-pixel is turned off or prevented from activating. As previously disclosed, each sub-pixel driving circuit510,520may be a simple TFT with its source connected to the data line, its gate connected to the scan line, and its drain connected to the gate of an OLED driver TFT. If pixel compensation is employed, then the driving circuit may be a multi-TFT driving circuit. In this example, T1connects the gate and source of the B1 driver TFT when Vdd B2 is activated, thereby shutting off the B1 sub-pixel when the B2 sub-pixel is energized.

Regardless of whether individual or shared driving circuits are used, the switchable data line (B2 Vdd in the examples ofFIGS. 4-5) may be controlled externally on the basis of each line being switched based on image content, in the cases where one or more sub-pixels connected to each line needs to display a deep blue B2 color. That is, the data line drive voltage or current may be set to render a desired sub-pixel luminance. An external controller may be used to ensure that sub-pixel intensity information transmitted by the data line is applied to the B1 or B2 sub-pixel depending which is needed at any particular time, with Vdd adjusted accordingly as described herein. The switchable voltage lines in a display panel as disclosed herein may be switched individually, or they may be switched in groups of 2 lines, 4 lines or any number of lines simultaneously. The trade off to the number of lines to be switched at the same time (i.e., the block size of the display arrangement) provides a tradeoff between increased use of deep blue sub-pixels on one hand, compared to the number and resolution of additional switchable B2 power lines on the other. It may be desirable to select a number of simultaneously-switched lines that matches a desired frequency of use of the deep blue B2 sub-pixels during operation of the display panel.

It can be seen by considering extension of the example circuits shown inFIGS. 4 and 5to a larger panel arrangement that devices disclosed herein may include fewer data lines per pixel than the number of colors of single-color sub-pixels within each full-color pixel. This may be the case even where multiple sub-pixels of a single color are used, such as where each full-color pixel includes multiple green, red, or yellow sub-pixels that may be activated in unison, for example. As a specific example, in the arrangement shown inFIG. 3A, each full-color pixel includes four colors of single-color sub-pixels—green, red, light blue, and deep blue. When used with a control circuit as shown inFIGS. 4-5, only three data lines may be needed since the light blue and deep blue sub-pixels share a single data line. That is, each full-color pixel in such a display would have four colors of sub-pixels but fewer than four data lines. The same general relationship holds where multiple sub-pixels of each color are used. For example, a similar arrangement having two deep blue sub-pixels in each pixel would still only use three data lines according to embodiments disclosed herein, since the light blue sub-pixel and the multiple deep blue sub-pixels within each pixel would use a single common data line.

In some embodiments, RGB data signals may be used to drive the pixel arrangements disclosed herein by adjusting the signal based on which blue sub-pixel is being used. That is, the RGB-type signal may be adjusted to account for a pixel formed from red, green, and light blue sub-pixels (an RGB1 pixel) or red, green, and deep blue (an RGB2 pixel). As previously noted, one type of pixel may be a “default” that is used unless the other is specifically needed, such as where an RGB1 pixel is used unless deep blue is needed, in which case an RGB2 pixel is used. Such mapping typically can be carried out in a graphics processing unit (GPU) or equivalent component of a display or a device providing video data to the display. Generally, in the embodiments disclosed herein each pixel will render a specific color, using either RGB1 sub-pixels when the specified color does not require B2, or RGB2 if it does require a deep or saturated blue. Individual RGB components may be calculated in real time for each pixel for each image.

One possible drawback or challenge of using a limited number of data lines and/or only activating deep blue sub-pixels in limited cases may appear to be a reduction in available color space, visible color quality, or similar. However, sub-pixel rendering allows for use of one deep blue sub-pixel for every 4, 8, or 16 full-color pixels for most OLED displays because the human eye has a much lower resolution for deep blue light than other colors. Accordingly, sub-pixel and pixel arrangements such as those shown inFIGS. 3A and 3Bmay be used. In such arrangements, even though the display panel is a “four color display,” the red, green and light blue fill factors can be the same or almost the same as they would be in a three-color RGB display. This is especially the case if there are only three OLED emissive layer (EML) depositions, for red, green and light blue, so that the same OLED EML deposition is being used for light blue and deep blue as this ensures that there does not need to be a masking alignment tolerance between the light blue and deep blue pixels, further improving their fill factor or aperture ratios. For example, a color altering component may be used in conjunction with a light blue emissive deposition to achieve deep blue emission. Examples of color altering components include color filters, color altering layers, up-conversion layers, down-conversion layers, and the like, including quantum dot layers, microcavities, doped organic layers, and the like, which are arranged in a stack with the appropriate portion of the light blue EML deposition. In this case the light blue and deep blue sub-pixels only need to be separated by an alignment tolerance in the backplane and not an OLED patterning alignment tolerance.

Although the examples provided above describe the use of a light blue sub-pixel in all cases unless a deep blue color is required, other arrangements may be used. For example, a similar display may be configured to use a deep blue sub-pixel unless a light (less- or unsaturated) blue is required to generate the desired color, in which case the deep blue sub-pixel may be deactivated and the light blue sub-pixel activated. Similar control circuitry may be used to the arrangements shown inFIGS. 4 and 5, where the light blue B1 sub-pixel includes a switched power line that turns off or disables the deep blue B2 sub-pixel when energized. Thus, in the case of a deep blue data line, all the pixels on that data line will render color based on the deep blue B2 sub-pixel, whereas in the case of a light blue data line, all the pixels on the data line will render color based on the light blue B1 sub-pixel. In either case, only one of the B1 or B2 sub-pixels is used at any given time in any given pixel, determined by whether any image for a given pixel connected to the same Vdd B2 line requires a deep blue sub-pixel or not. More generally, two sub-pixels of the same or a similar color may be used, where only one is active within a given pixel at a time. As another example, two red sub-pixels may be used, with one providing a deeper red than the other, i.e., a deeper peak emission wavelength. Such a configuration may be used where a highly saturated red emission is desired in some cases. The deep red sub-pixel may be relatively inefficient, in which case the lighter red sub-pixel may be used in cases where the specific deep red emission is not needed. This allows for improved overall display efficiency while still providing a deeper color saturation than otherwise may be possible.

Embodiments disclosed herein also may be used with other pixel arrangement types in addition to RGB1B2 architectures, which may include more or fewer sub-pixels in each pixel. For example, RGYB1B2 (red, green, yellow, light blue, deep blue) pixel arrangements may use similar arrangements in which fewer data lines per pixel are used than the number of colors of sub-pixels in each pixel. As a specific example, for an RGYB1B2 pixel that includes single red, green, yellow, light blue, and deep blue single-color sub-pixels, four or fewer data lines may be used. Such a configuration may include separate data lines for the red, green, and/or yellow sub-pixels, while using the same architecture for the B1 and B2 pixels as previously disclosed. Examples of RGYB1B2 and other pixel arrangements and associated devices and circuitry that may be suitable for use with the systems and methods disclosed herein are described, for example, in U.S. Pat. Nos. 9,385,168, 9,590,017, 9,424,772, 10,243,023, 10,304,906, and 10,229,956 and U.S. Pub. Nos. 2015/0349034 and 2015/0349032, the disclosure of each of which is incorporated by reference in its entirety.

Notably, embodiments disclosed herein may reduce, minimize, or eliminate the cost and complexity effects of using four or more sub-pixels in each full-color pixel within a display panel, while still providing the benefits typically associated with arrangements that use four or more sub-pixels. For example, as previously disclosed, pixel arrangements as disclosed herein may be fabricated by depositing not more than three separate emissive material layers or other deposition arrangements. This reduces the fabrication time, cost, and complexity of the device relative to other techniques for fabricating devices having four or more sub-pixels per pixel. Furthermore, sub-pixel rendering techniques may be used to reduce the effective reduction in fill factor that is typically expected when using four or more sub-pixels per pixel. As another example, the use of fewer data and/or gate lines per pixel relative to other arrangements that use four or more sub-pixels may provide cost, time, and complexity savings as well. As previously described, embodiments disclosed herein may allow for RGB1B2 type displays that have improved lifetime while using the same data and scan line architecture as used in a conventional RGB display.

Although examples provided herein are described with respect to OLED sub-pixels, such as shown inFIGS. 1-2, the same architectures may be used for other types of sub-pixels, including but not limited to microLED and quantum dot sub-pixels. That is, the architectures, arrangements, and devices described herein do not rely on any particular type of sub-pixel or emissive material to achieve the benefits described, but may be used with any device type that can be fabricated and connected in the manner shown and described. Such devices may be useful, for example, due to the desire to reduce deep blue emission generally for health reasons such as eye strain or injury, sleep cycle disturbance, and the like.

Furthermore, embodiments disclosed herein may apply equally to any emissive display that can benefit from using two different color blue sub-pixels, in addition to the OLED display panels shown and described herein. Such techniques may be useful to improve display health impacts by reducing deep blue emissions, and may improve display lifetime and/or efficiency by reducing the use of the deep blue sub-pixels. Examples of other suitable devices include microLED displays including mobile and television type displays, whether using a side by side architecture, or based on the downconversion of unpatterned blue and/or blue/green OLEDs or other emissive devices to produce a full color RGB image.