Display Power Consumption Research Articles

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

Power Control Technique Using Error Distribution Analysis for Ultrasound Imaging Displays

In this paper, a new power control technique based on clipped error distribution is proposed for portable ultrasound imaging displays. To reduce the display power consumption, the backlight dimming is used to select the optimal point between the power reduction of a backlight and the high image quality. In this case, the clipped error, i.e., the saturation error for pixels exceeding the maximum expressible gray level, should be considered. Conventional algorithms do not consider the clipped error distribution, which is the spatial distribution of pixels with the clipped error in a frame image when the power consumption is reduced. Therefore, it degrades the image quality in the medical display. On the other hand, the proposed algorithm calculates statistical values for clipped error distribution by analyzing the image characteristics. Hence, it can avoid degradation of the image quality by concentrating the pixels with clipped errors in a small region. In addition, the proposed algorithm uses a sampling technique, which only uses selected pixels based on the pre-defined sampling pattern, to reduce the computation time. Experimental results show that the proposed algorithm can improve the image quality in terms of peak signal-to-noise ratio by up to 7.063 dB (23.49%) while reducing the computation time by up to 0.451 μs (17.18%) using a sampling technique.

FocusVR

In this paper, we present the design and implementation of FocusVR, a system for effectively and efficiently reducing the power consumption of Virtual Reality (VR) devices by smartly dimming their displays. These devices are becoming increasingly common with large companies such as Facebook (Oculus Rift), and HTC and Valve (Vive), recently releasing high quality VR devices to the consumer market. However, these devices require increasingly higher screen resolutions and refresh rates to be effective, and this in turn, leads to high display power consumption costs. We show how the use of smart dimming techniques, vignettes and color mapping, can significantly reduce the power consumption of VR displays with minimal impact on usability. In particular, we describe the implementation of FocusVR in both Android and the Unity game engine and then present detailed measurement results across 3 different VR devices -- the Gear VR, the DK2, and the Vive. In addition, we present the results of 3 user studies, with 68 participants in total, that tested the usability of FocusVR. Overall, we show that FocusVR is able to save up to 80% of the display power and up to 50% of the overall system power, with negligible impact to usability.

High-Accurate and Fast Power Model Based on Channel Dependency for Mobile AMOLED Displays

Recently, active matrix organic light-emitting diode (AMOLED) displays have widely been used for user-interface applications on smartphones. Since frequent interactions between a user and a display which come from such applications tend to incur big display power consumption, the display power efficiency should be managed exactly and fast. For this purpose, a high-accurate and fast power model for AMOLED displays is greatly required for efficient power management. In this paper, we propose a novel high-accurate and fast power model for AMOLED displays, which is developed using a multiple regression technique to account for the dependency between R, G, and B channels and is polished using various performance optimization techniques. Then, the proposed model is applied to five AMOLED display panels of a CHIMEI panel and Galaxy S1, 3, 5, and 7 panels from SAMSUMG. The average error rates are obtained on these panels for four well-known image datasets. The proposed model shows the lowest error rate of 1.29% on Galaxy S7, while the simple model and Park’s model show the error rates of 6.91% and 6.57%, respectively. In addition, in order to guarantee the fast execution time of the proposed power model on smartphones, we implement performance optimizations to the model. For runtime application, the proposed power model is implemented at the operating system level of the Android smartphone equipped with Exynos 4412. The optimized power model shows an average execution time of approximately 7.77 milli-seconds per image displayed on the panel with 720x1280 resolution. Consequently, the proposed power model is shown to be very fast and accurate, and thus it is highly useful in smartphones with AMOLED displays.

80‐1: When is the Best Time to Switch Modes of Light Adaptable Displays for Lower Power and Better Visibility?

Light adaptable displays (LADs) were proposed for less power consumption and higher visibility regardless of ambient lighting conditions. LADs is a hybrid type of display comprising reflective and emissive (transmissive) displays. In this paper, we propose a new method to find when to switch the modes through a psychophysical experiments for the first time in the world. In order to find the optimum condition, we conduct psychophysical experiments for various reflectance of the reflective display. Through calculation, we compare power consumption of a liquid crystal display (LCD) and an LAD comprising LCD and reflective display, which verifies that the LAD can consume only 10–20% power of the LCD.

P‐7: A 65‐in. 8K LCD and OLED Display Using Cloud‐Aligned Composite Oxide‐Semiconductor (CAC‐OS) FET

Simulation results indicate the feasibility of displays manufactured under ultra‐high‐definition television standards by using a cloud‐aligned composite oxide semiconductor (CAC‐OS) FETs that exhibit high‐performance. The use of an oxide semiconductor/oxide conductor (OS/OC) pixel, which is a transparent pixel, reduced power consumption of a liquid crystal display.

Power Consumption and Temperature Distribution in WRGB Active-Matrix OLED Displays

In this paper, the power consumption of a white-red-green-blue (WRGB) active-matrix organic light-emitting device (OLED) display and the resulting temperature distribution across the display are analyzed as a function of the applied image and the luminance of the emitted light. It has been shown previously that temperature directly impacts the picture quality of an OLED display. Luminance, spectral radiance, power and temperature measurements are performed on a 55-in WRGB OLED display with a resolution of 1920 ×1080. A power model is presented that allows calculating the display's power consumption for a given applied image. This involves the dependency of the efficiency of the white OLED on the current density, the wavelength dependent transmission of the color filters and the contribution of each of the subpixels in producing the display's nominal white. The output of the power model is used as input for a basic thermal model that simulates the temperature distribution across the display. The thermal model is based on 3D computational fluid dynamics analysis framework (FloEFD). A good agreement between the simulations and measurements on the sample WRGB OLED display is obtained.

Low Image Distortion Constrained Power Saving for OLED Displays

Organic Light Emitting Diode (OLED) displays have matured into current smartphones. How to prolong the lifetime of displays while preserving the display quality becomes a primary issue. In this paper, we propose a low image distortion constrained power-saving approach for OLED displays based on gamma correction and saturation scaling. We first investigate the impact of gamma correction and saturation scaling on the power of emissive displays. The results show that changing the gamma and saturation value can obtain lower display power consumption when original image color maps to another one. Thus, we integrate the gamma correction and the saturation scaling into a new low-power approach for OLED displays. However, low gamma and high saturation lead to distortion on displaying. To guarantee user experience in this paper, the CIEDE2000 color difference formula and the Mean Structural Similarity Index (MSSIM) are used to evaluate the effectiveness of our approach. The results show that our approach saves up significant display power with high image quality.

Object–image‐based quality‐on‐demand energy saving schemes for OLED displays

This Letter studies how to precisely and instantly transform the object images displaying colours on an organic light-emitting diode (OLED) in order to meet both energy saving and personal viewing quality requirements. The proposed method could be applied to a real-time energy saving transformation of any display media on an OLED and it will save display power consumption up to 74% based on the predicted PSNR = 40 dB. At the same time, it still retains a very good image quality after transformation.

Low-Power Drive Method for MIM-Cathode Displays

A low-power drive method for reducing dissipation power by 75% is developed for cathodoluminescence displays using metal-insulator-metal (MIM) cathodes. The dissipation power is the power consumed in driver circuits for charging and discharging capacitive loads of a display panel. The drive method, called high-impedance (high-Z) drive method, reduces the panel's effective capacitance by connecting non-selected scan lines to high-impedance driver outputs. No visual crosstalk occurred in displayed images on a 3.8-cm-diagonal MIM-cathode display, regardless of significant induced voltages observed on the high-impedance scan lines. This insensitivity to the induced voltages is mainly because the polarity of induced voltages is reverse for electron emission. To reduce the induced voltage, an “enhanced high-Z drive method” is also developed. Analytical formulae to calculate the dissipation power and the amplitude of the induced voltages are devised on the basis of a capacitor model of the MIM-cathode array. Excellent agreement between measured and calculated results validates this model. On the basis of the capacitor model, the total power consumption of a 32-inch diagonal MIM-cathode display is estimated. This estimation indicates the total power consumption would be only 24 W including dissipation power at an average brightness of 200 cd/m .

Online OLED dynamic voltage scaling for video streaming applications on mobile devices

This work proposes an online DVS approach for OLED-based mobile video applications to reduce display power consumption. A time-efficient representative-region based DVS scheme is developed and applied in MPEG video streaming. Based on the proposed scheme, flexible DVS solutions can be adaptively derived according to timing constraints. Experimental results show a 26.9% power reduction while keeping 99.3% frames displayed in high quality.

Scene-Adaptive RGB-to-RGBW Conversion Using Retinex Theory-Based Color Preservation

This paper proposes a retinex theory-based approach to RGB-to-RGBW conversion that preserves the human color perception within a pre-determined level of color distortion for RGBW displays. The proposed method primarily consists of two procedures. In the first, it searches for the maximum intensity level that induces no color distortion for a given image by extracting the white spectra from the common components of the RGB primary colors and adjusting all the pixels' gains uniformly. In the second, the proposed method applies an additional gain to each pixel based on its chromaticness and controls the color distortions arising from the individual gains using the color perception estimated by retinex theory and a feedback mechanism. Experimental results showed that the proposed method was more effective than conventional methods in terms of intensity increment and color preservation. For Kodak test images, the proposed method increased the average intensity by 1.4987 times with a color-distortion level of 0.0094 compared to reference RGB displays, whereas the conventional methods increased the average intensity by 0.8624-1.3429 times with color-distortion levels of 0.0325-0.0682. The surplus intensity yielded by the proposed method can be used to dynamically reduce the power consumption of a liquid crystal display (LCD) backlight or to provide brighter images on LCDs.

Chameleon: A Color-Adaptive Web Browser for Mobile OLED Displays

Displays based on organic light-emitting diode (OLED) technology are appearing on many mobile devices. Unlike liquid crystal displays (LCD), OLED displays consume dramatically different power for showing different colors. In particular, OLED displays are inefficient for showing bright colors. This has made them undesirable for mobile devices because much of the web content is of bright colors. To tackle this problem, we present the motivational studies, design, and realization of Chameleon, a color adaptive web browser that renders webpages with power-optimized color schemes under user-supplied constraints. Driven by the findings from our motivational studies, Chameleon provides end users with important options, offloads tasks that are not absolutely needed in real time, and accomplishes real-time tasks by carefully enhancing the codebase of a browser engine. According to measurements with OLED smartphones, Chameleon is able to reduce average system power consumption for web browsing by 41 percent and is able to reduce display power consumption by 64 percent without introducing any noticeable delay.

Preparation and Performance Optimization of a Full Color Organic Light-Emitting Diodes Display Device

A full color 2.2″ passive matrix organic light-emitting diodes (OLEDs) with 128 (RGB) * 160 pixels was developed. The display features that driving circuit can transform 18 bits gray-scale data from a PC to the OLED panel via a DVI channel. The size of the pixel was 240μm240μm, while that of mono sub-pixel is 190μm45μm. The lifetime of panel was estimated over 5000h because of the use of dual-scan driving technology, and the power consumption of the display was 300mw about when the average luminance of panel reach 40cd/m2.

低功耗TFT-LCD驱动方法

A dual-gate + Z-inversion(DZi) driving method was proposed to reduce power consumption of thin-film transistor liquid crystal display(TFT-LCD).The power saving principle of DZi driving was researched,the structure design and circuit design were finished,35.6 cm(14 in) WXGA(1 366 RGB×768) samples were manufactured,and the power saving effect was measured and analyzed.As results,DZi can save TFT-LCD power consumption in effect,such as panel AVDDS power reduces 70%(191 mW) when display color-bar pattern.Moire phenomenon that appeared in DZi module was analyzed,and solutions were proposed.The research established a driving method and design reference for lower power consumption in TFT-LCDs and other displays.

Low Power 6.0-Inch Extended Graphics Array Reflective Liquid Crystal Display using Indium Gallium Zinc Oxide Semiconductor with Electronic Paper Function

We focused on the ultra-low leakage current of indium gallium zinc oxide (IGZO) field-effect transistors (FETs). The power consumption of an liquid crystal display (LCD) panel can be markedly reduced by significantly lowering frame frequency, i.e., stopping unnecessary data rewrites at the time of displaying still images. We successfully fabricated a 6.0-in. extended graphics array (XGA) reflective liquid crystal display (RLCD) panel integrally including a data selection demultiplexer and a scan driver and capable of displaying still images at 1/180 fps. Thus, the panel is suitable for electronic paper displays.

Intermediate pre-tilt angle control by a composite alignment thin film structure for liquidcrystal displays

We designed a patterned composite alignment thin film structure using a horizontalalignment polyimide (PI) layer and vertical alignment liquid crystal polymer (LCP) pillars.The LCP polymer precursor concentration was varied at 0–10% and the pillars wereintroduced by a photolithography process. Both single-sided and double-sided liquid crystaldisplay cells were assembled for a series of electro-optical characterization techniques. Thehorizontal PI alignment layer alone had a designated control of the pre-tilt angle of7° after the prescribed mechanical rubbing process. The pre-tilt angle was improved to24° when the LCP precursor concentration was 5%. It was further increased to61° at the concentration of 10%. In addition, the study on the electrical response time and graylevel variation demonstrated promising results for potential applications. The field-onresponse time was only 2.79 ms and the field-off response time was 0.35 ms for thedouble-sided liquid crystal display cells using a ramping voltage of 5.5 V. The effectivecontrol of the cell pre-tilt angle suggested that the display power consumption and responsetime would be greatly improved.

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

Ambient light sensors have been used to reduce power consumption of Active Matrix Liquid Crystal Displays (AMLCD) adjusting display brightness depending on ambient illumination. Discrete sensors have been commonly used for this purpose. They make module design complex. Therefore it has been required to integrate the sensors on the display panels for solving the issue. So far, many kinds of integrated sensors have been developed using Amorphous Silicon (a-Si) technology or Low Temperature Polycrystalline Silicon (LTPS) technology. These conventional integrated sensors have two problems. One is that LTPS sensors have less dynamic range due to the less photosensitivity of LTPS photodiodes. The other is that both the LTPS and a-Si sensors are susceptible to display driving noises. In this paper, we introduce a novel integrated sensor using both LTPS and a-Si technologies, which can solve these problems. It consists of vertical a-Si Schottky photodiodes and an LTPS differential converter circuit. The a-Si photodiodes have much higher photosensitivity than LTPS ones, and this contributes to wide dynamic range and high accuracy. The LTPS differential converter circuit converts photocurrent of the photodiodes to a robust digital signal. In addition it has a function of canceling the influences of the display driving noises. With the circuit, the sensor can stably and accurately work even under the noises. The performance of the sensor introduced in this paper was measured to verify the advantages of the novel design. The measurement result showed that it worked in a wide ambient illuminance range of 5-55, 000lux with small errors of below 5%. It was also verified that it stably and accurately worked even under the display driving noise. Thus the sensor introduced in this paper achieved the wide dynamic range and noise robustness.

34.2: Invited Paper: Development of 1m × 2m Plasma Tube Array PTA Technologies Ready for Ultra‐Large Film Display

AbstractThe plasma tubes array is expected to realize the next generation of wall size display because of its wonderful characteristics such as ultra‐thin, light‐weight, flexible and low power consumption. We had successfully developed a prototype film display of 1m × 2m screen size which was consisted of 4 sub‐modules of 0.5m × 1m with the seam width under 1mm. The weight, thickness and power consumption of the film display were measured at 2.5kg, 1mm and 400W respectively.

P‐46: Optimization of Subpixel Color Tiles for Mobile Displays

AbstractA key issue for the optimization of subpixel color tiles for mobile displays is to maximize the image quality, often defined in terms of brightness or reflectance, and color saturation, while minimizing display power consumption. for the mirasol™ display based on MEMS technology, the RGBY quad is found to be a structure that achieves a balance between reflectance and color saturation. Simulation results based upon demonstration devices are presented with discussions about proper image quality metrics for mobile displays.