Journal of the Society for Information Display最新文献

The cover image is based on the Special Section Paper Next generation personalized display systems employing adaptive dynamic-range compression techniques to address diversity in individual circadian visual features by Sakuichi Ohtsuka et al., https://doi.org/10.1002/jsid.1277

The SID logo is reproduced with permission of the Society for Information Display.

The measured spatial resolution of augmented reality head-mounted displays (AR HMDs) is determined by three components: optics, display, and the rendering pipeline, which includes the anti-aliasing method. Therefore, separating and quantifying the contributions from these components is necessary for evaluating the spatial resolution of AR HMDs. We demonstrate a method for quantifying the contributions from the optical performance and the rendering pipeline on the spatial resolution of AR HMD using point-spread function (PSF) analysis. In this method, an imaging photometer captures a series of rendered scenes on the AR HMD that consist of arrays of spheres of increasing sizes with different anti-aliasing (AA) methods. The contributions from the optics, display, and anti-aliasing methods can be separated, and we find that temporal anti-aliasing (TAA) and multisample anti-aliasing (MSAA) are in good agreement with the performance of no AA. However, fast approximate anti-aliasing (FXAA) results in decreased luminance for smaller rendered targets and a different spatial resolution for larger targets. Finally, we repeated our methods on multiple HMDs and characterized the dependence of the spatial resolution across the field of view. These measurements show significant non-uniformity in the optical contribution to the spatial resolution.

A new flexible low-temperature polycrystalline silicon thin film transistors (LTPS TFTs) on PI substrate with organic ILD layer, island TFT, and TFT channel perpendicular to stress direction was proposed. AMOLED display panel manufactured with organic ILD did not show any visible degradation of panel image after outward rolling cycles of 200,000 at rolling radius of 4 mm or inward folding cycles of 200,000 at folding radius of 1 mm. Another novel structure of TFT with channel perpendicular to stress direction significantly reduced change of threshold voltage of −0.03 V compared with change of threshold voltage of −0.6 V for TFT with channel parallel to stress direction for reliability test of high drain current (HDC) after 100,000 outward-bending cycles at bending radius of 3 mm. After inward-bending cycles of 200,000 at bending radius of 1 mm, reliability test results for TFT device with organic ILD layer showed that change of on-current is 10.07% for hot carrier instability (HCI) test, change of threshold voltage −0.31 V for negative bias thermal instability (NBTI) test, change of threshold voltage −0.24 V for hysteresis test, and breakdown voltage of gate insulator 7.73 MV/cm, respectively, and these performances are similar to those of TFT device with inorganic ILD (SiN_x).

When viewing the mini-LED display screen from a large angle, the seam appearing at the edge of the module can disrupt the uniformity of the entire screen's bright state. This paper studies the formation mechanism of bright and dark seam and color seam from the perspectives of spatial frequency and packaging structure, derives the formula for spatial frequency, analyzes the optical path at the splicing position, and designs a reasonable packaging film structure to solve the color seam.

This paper presents a method of monolithically integrating gallium nitride micrometer-scale light-emitting diodes (microLEDs) with an indium gallium zinc oxide (IGZO) thin-film transistor (TFT) backplane to produce an active-matrix microdisplay. After discussion of the fabrication process, individual LEDs, TFTs, and the integrated system are characterized. Results demonstrate a 32 × 32 pixel, 78.4 PPI microdisplay with luminance exceeding 1500 nits. The dynamic set and hold behaviors of the active-matrix pixel circuit are analyzed to verify the applicability of this technology for use in high and low refresh rate displays.

This paper presents an OLED display driver IC with high-gain fast-slew (HGFS) and on-the-fly self-repair (OFSR) circuits for a spatial resolution of WQHD and a frame rate of 120 Hz. The proposed HGFS circuit increases the slewing current of the unity-gain amplifier of the source driver when the input voltage is largely changed, reducing the settling time of the source driver as the resolution and frame rate increase. To enhance image quality by correcting line defects, the OFSR circuit replaces a faulty channel with a spare dummy channel. The OLED display driver IC was manufactured using a 28-nm high-voltage process with 8 V/20 V transistors and has 2880 source drivers for WQHD display. The measurement results indicate a horizontal line time of 2.7 μs with a slew rate of 7.675 V/μs, supporting WQHD resolution and 120-Hz frame rate. The displayed image demonstrates that the vertical line defect has disappeared with the use of OFSR.

Usually, the resolution loss is severe in light-field display due to the spatial multiplexing of several neighboring pixels to display images from different directions. However, limited by the resolution of the flat panel display, the light-field 3D display shows insufficient display size, 3D image depth, or resolution. This article uses optimized ferroelectric liquid crystal (FLC) shutters with high contrast (~1000:1), ultra-fast response (<20 μs), and polarity-related binary switching at low operating voltage (5 V). This article utilized 32 time-sequentially opened FLC light valve arrays refreshed at 2 kHz to display images from different directions. Because of the polarity-sensitive switching nature of FLC, the reverse phase induces serious crosstalk between different images. This work uses the timing synchronization method of dual-FLC liquid crystal cells to achieve independent control of 32 light valves without reverse phase, reducing the crosstalk and increasing the equivalent 3D resolution by multiplexing the flat panel display 32 times within 60 Hz.

The polarization-independent liquid crystal (LC) phase modulators can greatly improve the efficiency and reduce the complexity of the optical system. However, it is difficult for the LC phase modulator to achieve both good low-loss modulation and polarization-independent properties. A LC phase modulator of single layer microdomain twisted structure has been proposed to achieve good polarization independence and low loss in phase modulation. However, the multi-exposure in fabrication is difficult to realize in production process. To simplify the fabrication process, an alternate LC (ALC) mask is proposed with the alternate arrangement of twist-nematic (TN) LC and nematic LC. The fabrication process is optimized to two steps exposure with the usage of ALC and is suitable for large-amount-production. The measurement results showed that the single layer microdomain twisted LC phase modulator may get very low polarization dependence, about 3.52% under 2π phase modulation depth, with low loss. The device shows good potential application in optical communication, wearable device, and display.

Display technologies have been developed to adjust the display brightness and color under different viewing conditions, providing better viewing experiences to users. Solutions have been proposed to adjust the display white point according to the ambient light condition, which roots into the underlying chromatic adaptation mechanism in the human visual system. This study was carefully designed to reveal the necessity to consider the ambient light level and display luminance together, which affects the viewing mode, when adjusting the adaptive display white point. The results clearly suggested that when the display luminance was greater than the ambient light diffuse white luminance, the display was viewed in the self-luminous mode and the display white point was not significantly affected by the ambient light chromaticities. In contrast, when the display luminance was lower than the ambient light diffuse white luminance, the display was viewed in the surface mode and the ambient light chromaticities had a significant effect on the display white point, especially when the surround ratio was high.

Thermally activated delayed fluorescent (TADF) and phosphorescent blue organic light-emitting diodes (OLEDs) have been developed to overcome the relatively low triplet exciton utilization of traditional fluorescent OLEDs. However, broad emission spectra originating from charge transfer process limit the commercial application of such blue OLEDs. Herein, an effective phosphor-sensitized fluorescent (PSF) OLED device structure was designed. PSF OLED exhibited a maximum blue index (BI) of 508 cd/A/CIEy with CIEy of 0.060, which has been the highest efficiency result reported for PSF deep-blue OLEDs. A nearly 100% improvement in operational lifetime LT₉₅ (L/L₀ = 95%) was achieved successfully by using lower triplet energy (T₁) and deuterated host materials. Impressively, the sensitized OLEDs maintained BI of 407 cd/A/CIEy, narrow emission spectra (FWHM = 17 nm), and high color purity (CIEy = 0.046), revealing the attractive technical advantages and commercial application potential.