spd lcd panel quotation

If you’re just starting your research onsmart glass, you’re probably seeing the two most common types pop up:SPDandPDLC. While industry professionals know the difference between the two, these terms are foreign to most, leaving the majority of people wondering: what differentiates SPD from PDLC? And, which of these two smart glass technologies are right for me?

SPDstands for Suspended Particle Devices (rod-like particles that are suspended in a matrix). SPD can block up to 99% of light, making it ideal forcustom shading in outdoor windows, and not a solid privacy solution. Switching speed is up to 3 seconds, no matter the size of the glass — significantly faster than other active glass technologies used for shading. Haze is as low as 2.5% — depending on post processing and the manufacturer. Because of its shading capabilities, SPD is found in cars, planes, trains, or in architecture as it can contribute to LEED points, making projects greener and more energy efficient.

Because of it’s tinting and shading capabilities, SPD smart glass is outdoor grade, and most commonly found in theautomotive sector,creating smart windows in sky facing glass like the sunroof of the McClaren or Mercedes S-Class, which shades or tints to custom degrees for reduced glare, fuel consumption, and

Until today, architects and interior designs were most likely to use Liquid Crystal Glass for interior “WOW Factor” while the transportation industry turned to EDW’s (electronically dimmable windows) with SPD. However, we stand at the beginning of a new era where smart glass is redefining the industry standards.

Material science companyGauzyis now manufacturing SPD with architectural widths making it ideal for skylights, facades, and curtain walls. They are also bringing LC based films outdoors with its High Temp and Solar Reflective technologies. This breakthrough is opening new opportunities for OEM’s and Tier-1 suppliers to integrate PDLC into car windows for location and time based advertising and IR light reflection.

As smart glass technology continues to make its way into mainstream automotive and architectural applications, the way we interact with glass, and light, will change drastically. Both Liquid Crystal Glass and glass with SPD technology, also known as LCG® (light control glass) are key contributors towards the push for integration of smart materials across sectors.

Serial Peripheral Interface (SPI) is a synchronous serial communication interface best-suited for short distances. It was developed by Motorola for components to share data such as flash memory, sensors, Real-Time Clocks, analog-to-digital converters, and more. Because there is no protocol overhead, the transmission runs at relatively high speeds. SPI runs on one master (the side that generates the clock) with one or more slaves, usually the devices outside the central processor. One drawback of SPI is the number of pins required between devices. Each slave added to the master/slave system needs an additional chip select I/O pin on the master. SPI is a great option for small, low-resolution displays including PMOLEDs and smaller LCDs.

Philips Semiconductors invented I2C (Inter-integrated Circuit) or I-squared-C in 1982. It utilizes a multi-master, multi-slave, single-ended, serial computer bus system. Engineers developed I2C for simple peripherals on PCs, like keyboards and mice to then later apply it to displays. Like SPI, it only works for short distances within a device and uses an asynchronous serial port. What sets I2C apart from SPI is that it can support up to 1008 slaves and only requires two wires, serial clock (SCL), and serial data (SDA). Like SPI, I2C also works well with PMOLEDs and smaller LCDs. Many display systems transfer the touch sensor data through I2C.

Low-Voltage Differential Signaling (LVDS) was developed in 1994 and is a popular choice for large LCDs and peripherals in need of high bandwidth, like high-definition graphics and fast frame rates. It is a great solution because of its high speed of data transmission while using low voltage. Two wires carry the signal,  with one wire carrying the exact inverse of its companion. The electric field generated by one wire is neatly concealed by the other, creating much less interference to nearby wireless systems. At the receiver end, a circuit reads the difference (hence the "differential" in the name) in voltage between the wires. As a result, this scheme doesn’t generate noise or gets its signals scrambled by external noise. The interface consists of four, six, or eight pairs of wires, plus a pair carrying the clock and some ground wires. 24-bit color information at the transmitter end is converted to serial information, transmitted quickly over these pairs of cables, then converted back to 24-bit parallel in the receiver, resulting in an interface that is very fast to handle large displays and is very immune to interference.

A class action lawsuit alleged a detailed conspiracy from the late 1990s through 2006 to fix LCD prices, resulting in higher costs for buyers of televisions, laptops and other electronics. Several companies also pleaded guilty to separate criminal charges and paid fines.

Toshiba spokeswoman Deborah Chalmers said the company “denies any wrongdoing on its part in the LCD business, and it entered into the settlement to avoid further expense and the distraction of protracted litigation.”

Before evaluating the color gamut of an LCD, let us first elucidate its definition, as this definition is sometimes confusing and misleading. Several standards have been proposed to quantify color gamut (for example, sRGB, Adobe RGB, NTSC and so on). Here we focus on the most comprehensive standard, called Rec. 2020, with RGB lasers. Rec. 2020 covers all the existing standards17, 18). Although CIE suggests using CIE 1976, as it is a color uniform space, many display makers and research groups are still using CIE 1931 to display their results. To satisfy both camps, here we present a color gamut in both CIE 1931 and CIE 1976.

In an LCD, the backlight passes through the LC layer and CFs before reaching the viewer. Therefore, we have to incorporate the backlight spectra (Figure 1) into the LCD panel to calculate the output spectral power distribution (SPD)ɛ<0) LCFigure 2a). Such an LCD has been widely used in smartphones and pads. The wavelength-dependent refractive indices of the employed LC are also considered in the simulation. Figure 2b–2d depicts the obtained SPD for the RGB primary colors with or without Gaussian fitting. In both cases, light leakage for all three channels is observed clearly, especially for the blue channel, where a fairly large bump leaks through the green CF. For the real spectrum without Gaussian fitting, the light leakage is even worse, owing to the long-emission tails, which further deteriorate the color purity.

In the CIE 1931 color space, the color gamut with Gaussian fittings is 6.6% wider than that using the real spectra, whereas in CIE 1976, this difference is 6%. For different CFs and light sources, this discrepancy varies. However, Gaussian-fitted curves lead to a wider color gamut than using the real emission spectra. Therefore, to establish the theoretical limit of the color gamut of an LCD, we use the Gaussian-fitted spectra.

From Table 1, the color gamut without Gaussian-fitted spectra is ~83% Rec. 2020. To improve that, we fine-tuned the emission spectrum of QD and OIP to match the transmission bands of CFs, as Figure 4 demonstrates. However, tuning the peak emission wavelength influences the light efficiency, because the human eye has different sensitivities to different colors. This is governed by the human eye sensitivity function V(λ), which peaks at 555 nm. Therefore, we introduced another metric, the total light efficiency (TLE), to characterize how much input light transmits through the LCD panel and finally gets converted to the brightness perceived by the human eye

Both color gamut and TLE are important parameters for a display device. For such a multi-objective problem, different objectives may be mutually exclusive. In short, any further improvement of one objective (for example, color gamut) is likely to be compromised by the degradation of another objective (for example, TLE). Therefore, a Pareto front is commonly employed, and all solutions will fall either on or below this Pareto front (see Supplementary Information for more details). Figure 5 is a plot of the calculated Pareto fronts of the LCD using backlight with different FWHM values.

From Figure 5, several interesting phenomena are observed. First, there is an inherent tradeoff between light efficiency and color gamut. Thus, a delicate balance should be chosen in practical applications. Second, for a backlight with the same FWHM, there is indeed a theoretical limit for the color gamut, regardless of the RGB central wavelengths. For example, when the FWHM of QD or OIP emission spectrum is 30 nm, the largest achievable color gamut is 90.1% Rec. 2020 in CIE 1931 (Figure 5a) or 91.5% Rec. 2020 in CIE 1976 (Figure 5b). Next, we find that as the light source becomes more saturated (that is, a narrower FWHM), the maximum color gamut increases and then gradually saturates. Currently, the commercial Cd-based QD-enhanced backlight exhibits a 30-nm FWHM, and it could reach 25 nm in the next few yearsFigure 5, the color gamut improvement is only 2%. Even if the FWHM of the light emitters were laser-like (≤1 nm), the maximum color gamut is ~93.5% Rec. 2020. This limits the color gamut that an LCD can possibly achieve. Please note that this limit is obtained with Gaussian-fitted spectra; it would be lower if real spectra are used.

We have found the theoretical limit of the color gamut of an LCD, as shown in Figures 5 and 7. It is jointly determined by the light source (central wavelength and FWHM) and the CFs (crosstalk). Even if we reduce the FWHM of the backlight to 1 nm, the color gamut is still limited by the crosstalk of the blue/green and green/red CFs (Figure 2). Narrowing the transmission bands (CF-2) could mitigate this issue but not completely. Meanwhile, the optical efficiency is substantially compromised. This tradeoff may not be worthwhile. Therefore, as long as the CF technology makes no disruptive progress, the color gamut of an LCD will be limited, even if the backlight source exhibits laser-like narrow emission spectra.