can cold temperatures kill an lcd touch screen made in china

Smartphones are the opium of the people. If you need proof, just watch the average person’s reaction when they break “their precious”. Repairing smartphones has become a huge business. The most often broken item on phones is of course the front glass. In most cases, the screen itself doesn’t break. On newer smartphones, even the touchscreen is safe. The front glass is only a protective lens.

The easiest way to repair a broken front glass is to swap the entire LCD assembly. For an iPhone 6 plus, this will run upwards of $120 USD. However, the glass lens alone is just $10. The problem is that the LCD, digitizer and front glass are a laminated package. Removing them without breaking the wafer thin LCD glass requires great care. The hardest part is breaking down the optical glue securing the glass to the LCD. In the past that has been done with heat. More recently, companies from China have been selling liquid-nitrogen-based machines that cool the assembly. Now immersing a phone screen in -196° C liquid nitrogen would probably destroy the LCD. However, these machines use a temperature controller to keep a surface at -140° C. Just enough to cause the glue to become brittle, but not kill the LCD.

[JerryRigEverything] doesn’t have several thousand dollars for a liquid nitrogen machine, but he does have a $5 block of dry ice. Dry ice runs at -78.5°C. Balmy compared to liquid nitrogen, but still plenty cold. After laying the phone screens down on the ice for a few minutes, [Jerry] was able to chip away the glass. It definitely takes more work than the nitrogen method. Still, if you’re not opening your own phone repair shop, we think this is the way to go.

Broken phones are a cheap and easy way to get high-resolution LCD screens for your projects. The problem is driving them.[Twl] has an awesome project on Hackaday.io for driving phone screens using an FPGA. We haven’t seen it done with iPhone 6 yet though. Anyone up for the challenge?

No way in heck would I leave my scope (a Rigol) out in the garage. I have most of my stuff in an unheated storage unit at the moment and while I"m not using the scope for anything currently, it is still waiting patiently in my bedroom. I think you made the right choice by being more careful with yours as well.

When I said earlier that LCDs don"t like the cold... they can actually crack or otherwise completely break. I wasn"t just referring to sluggish performance, though sluggish performance is almost a definite in the cold whereas cracking is just a slight possibility (if your equipment is good).

I don"t know if a freezer would get the units cold enough to see what happens. I"ve used both grayscale and coler etrex units outside in the winter, and find they"re good to a little below zero fareheit most of the time if you use lithium batteries. Somewhere around zero or a little below, the sreen will get really sluggish, and start doing strange stuff where only parts of it update and stuff like that. The unit will keep recording good tracks though long after the display stops working. On the other end of the spectrum, having taken the Grayscale units into the desert many a time, I can report that direct hot sun on the display will cause the constrast to change to the point you can"t read the screen anymore, and that with eTrex units or a G-III at least you can"t adjust the constrast enough to make them useable. I haven"t observed similar behavior with color units yet though.

On the Teton snowshoe backpacking trip I went on where it got cold enough to cause my VistaC display to fail, I just used the lanyard and kept it inside my coat worn around my neck most of the time. You can then pull it out and use it for a considerable amount of time before it gets cold enough to cause any problems. Other than the rare occasion, most of time though I don"t expose my units to the cold for a long enough period of time to experience problems. As I age, I find I"m a lot less likely to expose myself to that sort of condition. (Who knows, maybe it"s wisdom)

The TFT LCD screen display, for the general masses, is no longer a difficult noun. And it is another after semiconductor could create a large number of emerging technology products of the business turnover, more because of its features, thin so it than using the application scope of the cathode ray tube (CRT, cathode ray tube) display made by wider. Today, I’m going to talk about how the TFT LCD Touch Screen Display Works.

As I mentioned earlier, liquid-crystal displays (LCDs) refer to a bunch produced by using the TFT screen LCD display. Now for LCD displays the name is directed mostly used in notebook computers, or desktop computer applications display. Is the thin film transistor TFT LCD display. Abbreviation of TFT LCD. This kind of display form has two main characteristics, one is a thin film transistor, the other is TFT LCD itself. Let’s talk about the TFT screen itself.

We usually think of substances like water as three states, solid-liquid, and gas. The three states of material actually are for water, for different materials, a different state may exist.

As we want to talk about liquid crystal state is concerned, it is a state between solid and liquid, actually, this kind of state is only part of the material of a kind of phase change process (see figure 1), as long as the material has the above process, namely the state exists between solid and liquid, a physicist called liquid crystal.

This type of TFT LCD screen was first discovered, had been spent more than one hundred years ago. In 1888 AD, the Austrian botanist Friedrich Reinitzer, found in the observation from the plant refined out of benzoic acid cholesterol (cholesteryl benzoate) found that when the melting behavior of the compound heated to 145.5 ℃, Solid can melt, presents a kind of solid phase and liquid phase between the half gonorrhea melt flow of the liquid. This situation will always maintain ℃ temperature rise to 178.5 degrees, to form a clear isotropic liquid (isotropic liquid).

The next year, in 1889, the study of thermodynamic equilibrium and the phase transfer German physicist O.L Ehmann, compounds for a more detailed analysis of this. He found that under the polarizing microscope, half of the viscous liquid gonorrhea liquid compounds with different parts peculiar to the crystal birefringence (birefringence) of the optical properties, namely, optical interphase (optically anisotropic). It will be a name to this as the liquid crystal. Since then, scientists will be the nature of this new discovery, known as the fourth state material – LCD (liquid crystal). It at a specific temperature range can have the characteristics of the liquid and solid at the same time.

General with water, solid lattice in heating because it is over, began to heat and destroy the lattice, when the temperature exceeds melting point will be dissolved into a liquid. And cause the type of liquid crystal is different (see figure 2), when the solid heat does not directly into the liquid, will be dissolved to form a liquid crystal state. When you continue heating, it will only then dissolve into a liquid (isotropic liquid). This is called the secondary dissolution phenomenon.

The liquid crystal state, as the name implies, will be a solid lattice and the liquid. When the liquid crystal was found, because of a lot of more phyletic, In 1922, the results observed by g. Friedel with a polarizing microscope divided liquid crystals into Nematic Smectic and Cholesteric categories. However, if they were classified according to the order of molecular arrangement (see figure 3), they could be divided into the following four categories:

Its structure is composed of TFT LCD molecules stick together, forming a layer structure. It’s every layer of the molecular long axis direction parallel to each other. And the long axis direction for each layer plane is vertical or a tilt Angle. Due to its structure is very similar to crystals, so they are called phase. The order parameter S (the order parameter) tend to be 1. Type in layered crystal layer and interlayer bonding can fracture because of temperature, so the layer and interlayer sliding more easily. But each layer within the molecular bonding is stronger, so it is not easy to be interrupted. Therefore in the context of the monolayer, Its arranged orderly and viscosity is bigger. If we use the macroscopic phenomenon to describe the physical properties of liquid crystal, we can make a group of regional average points as the liquid crystal molecules are pointing in the direction of the arrow (director), which is the direction of a group of liquid crystal molecules regional average. And with lamellar liquid crystal, because of its structure, the TFT LCD molecules will cambium-like so can point to a vector of different classification of the different lamellar liquid crystal again. When the long axis of the liquid crystal molecules are vertical stand, Call it “Sematic A phase.” if stand long axis direction of the TFT LCD molecules have some Angle of tilt (tilt), call it “Sematic C phase”. In A, C and other letters to name, which was discovered in accordance with the order to address, and so on, there should be A “Semantic phase B is.” but later found A deformation phase B is C phase, And the liquid crystal molecules in the structure layer by layer, in addition to each layer of TFT LCD molecules have tilt Angle, the tilt Angle between layer by layer will form a helical structure.

Nematic is a Greek word, the word mean in the thread is the same as in English. Mainly because with the naked eye to observe the liquid crystal, it looks like a silk pattern. The LCD screen molecules on the space of the regular arrangement of one dimension, all rod long axis of the liquid crystal molecules will choose a particular direction (that is, pointing vector) as the main shaft and arranged parallel to each other. And don’t like lamellar liquid crystal has a layered structure. Compared with the layer column type liquid crystal alignment is no order, That is to say, its order parameter S is smaller than the lamellar liquid crystal, and its viscosity is smaller, so it is easier to flow (its flow mainly comes from the free movement of molecules in the long axis direction). Linear liquid crystal is the common TFT LCD display screen TN(Twisted nematic) type liquid crystal.

Most of the sources of the name, because are generated by the derivative of the cholesterol. But some without cholesterol structure of LCD screen with this liquid crystal phase. This kind of liquid crystal as shown in figure 5, if it is a layer of a layer to separate, would very much like a linear LCD screen. But look at the Z-axis, may find it pointing in the direction of the arrow will with layers and layers of different distribution, like a spiraling when the pointing vector rotate 360 degrees for molecular layer thickness is called a pitch. Because of its every layer like linear LCD, so also known as Chiral nematic phase. In terms of cholesterol crystal, and pointing in the direction vector of the vertical distribution of LCD screen molecules, due to the different point to vector, will have the different optical or electrical differences, thus has produced different features.

If we are according to the molecular weight of high and low points can be divided into liquid crystal polymer (polymer liquid crystal, the polymer in many of the liquid crystal molecules) and low molecular liquid crystal. This kind of classification of TFT LCD belongs to the application of the low molecular liquid crystal. If the reasons for the formation of liquid crystal state, because it can be divided into type temperature formation of liquid crystal state to a liquid crystal (thermotropic), and because of the concentration and the formation of a liquid crystal state type lyotropic liquid crystal (lyotropic).

In the classification of the mentioned before, Lamellar liquid crystal and liquid crystal of the linear type liquid crystal to cause the more common, as the temperature changes and form liquid crystal state. For the lyotropic liquid crystal, we need to consider the situation of molecules dissolved in a solvent. When the concentration is low, the molecular and mixed and disorderly, which are distributed in the solvent of the isotropic solution, but when higher concentration is greater than a certain critical concentration, because the molecule has no enough space to form mixed and disorderly, the distribution of molecular began to gather to form part of the rules, To reduce the space of the block. Therefore form different sex (anisotropic).

The solution so types lyotropic TFT screen molecules in the appropriate solvents reaches a certain critical concentration, the formation of liquid crystal state. Type lyotropic liquid crystal is one of the best examples that is soap. When soap bubbles in the water will not be at once into a liquid, and the bubble in the water for a long time, after the formation of white matter, is its liquid crystal state.

Due to the structure of the liquid crystal molecules for different parties (Anisotropic), so caused by the photoelectric effect will vary because of a different direction, in short, that is, the liquid crystal molecules in the dielectric coefficient and refractive index, and so on photoelectric properties have different sex, so we can use these properties to change the intensity of the incident light, so that the formation of gray-scale, to apply on the display component. We’ll discuss below, is one of the characteristics of liquid crystal belongs to the optical and electrical related, about the following items:

Our dielectric coefficient can be separated into two directions respectively is epsilon / / (and point to parallel component) and epsilon coming (a component perpendicular to the pointing vector). When the epsilon / / > epsilon coming then called the dielectric coefficient of different parts of LCD, can be used in parallel coordination. And epsilon / / < epsilon is called the dielectric coefficient of the different part coming negative type of TFT screen, only can be used in vertical coordination will need the photoelectric effect. When the applied electric field, the liquid crystal molecules will vary with dielectric coefficient is positive or negative, To determine whether the orientation of the liquid crystal molecules is parallel or perpendicular to the electric field, to determine whether the light penetrates. Now on most commonly used type TN LCD TFT LCD that belongs to the dielectric coefficient are type liquid crystal. When the dielectric coefficient of square difference Δ epsilon (= epsilon / / – epsilon) comes, the greater the LCD of the critical voltage (threshold voltage) will be smaller. So the LCD can be in the low voltage operation.

Liquid crystal molecules are also known as heterotropic crystals because they are mostly formed from rod-like or saucer-like molecules, and thus have different physical properties that are parallel to or perpendicular to the long axis of the molecule. Like the dielectric perp, the refractive index is also divided into vectors perpendicular to and parallel to the vector, namely, n // and n perpendicular to each other.

In addition, for uniaxial crystal, there are two different definitions of refraction coefficient, one is no, which refers to the refraction coefficient of ordinary ray, so it is shortened to no, and ordinary ray refers to the electric field component of its light wave is perpendicular to the optical axis, and the other is ne, which refers to the refraction coefficient of extraordinary ray. The extraordinary ray is referred to as the light of the electric field component parallel to the optical axis. At the same time, it defines the birefringence (birefringence) Δ n = no-no for the above two refractive index differences.

In accordance with the described above, the lamellar liquid crystal, linear liquid crystal, and LCD screen for cholesterol levels, because of its long liquid crystal molecules like a stick, so point to the direction of the vector and the molecular long axis parallel. To be defined with reference to the refraction coefficient of a single optical axis crystal, it will have two refractive indexes, respectively is perpendicular to the direction of the long axis of the liquid crystal n coming (= ne) and parallel to the long axis of the liquid crystal direction n / / (= no), so when the incident light liquid crystal, will be affected by two refractive indexes, cause in the vertical long axis of the liquid crystal and LCD long axis parallel to the direction of the speed of light will be different.

If with the molecular long axis parallel to the direction of light speed, when less than perpendicular to the speed of the molecular long axis direction, which means that parallel the molecular long axis direction of refractive index is greater than the vertical direction of the refractive index (because the refractive index is inversely proportional to the speed of light), is the one – no > 0. So the birefringence Δ n > 0, we think that it is called optics is a type of LCD, and lamellar liquid crystal and LCD are all belong to the optical is almost linear LCD. If the light of the parallel to the direction of the long axis was faster, On behalf of the flat to the governor of the axis of the refractive index is less than the vertical direction, so the birefringence Δ n < 0. We call it is the optical negative type of LCD. The cholesterol liquid crystal optical negative type of LCD.

For example, the elastic constant (kappa 11, kappa 22, kappa 33) contains the three most important constants: kappa 11 is the elastic constant at splay, kappa 22 is the elastic constant at the twist. Kappa 33 refers to predominating the elastic constants of bending (bend). The other as the coefficient of viscosity (viscosity coefficients and eta), will affect the rotational speed of the liquid crystal molecules with reaction time (response time), its value as small as possible. But this feature is affected by temperature is the largest. In addition to magnetic susceptibility (magnetic susceptibility), but also because of liquid crystals of different sex, Divided into c / / c coming. And the difference of magnetic susceptibility is defined as Δ c = c / / – c coming. In addition to the conductance coefficient (conductivity), and so on the photoelectric properties. Liquid crystal properties of the most important are the dielectric coefficient and refractive index of liquid crystal. The dielectric coefficient is determined liquid crystal under the influence of the electric field to the characteristics of the liquid crystal molecules, while the refractive index is liquid crystal in the light of its important parameters influencing the light path. The LCD is in using the liquid crystal itself of these features, the appropriate use of voltage, to control the rotation of the TFT LCD molecules, in turn, affect the direction of the light, to form different grayscale, a tool for displaying images. Of course, LCD itself is not alone as the monitor, also need other materials to help, Below, we will introduce the composition of various materials and operating principle of TFT LCD display.

I remember in high school physics class, when to teach the relevant physical properties of light, to do a lot of physical experiments, the purpose is to prove that light is a wave. And the marching direction of light waves, and the electric field and magnetic field perpendicular to each other. Light itself of the electric field and magnetic field component at the same time also is perpendicular to each other. That is to say with the electric field and magnetic field component direction, each other is two parallel to each other. (see figure 7) and the role of the polarizing film is like a fence, usually will be cut off a component perpendicular to the fence, With a fence parallel component only permitted through. So if we picked up a piece of the light polarization slabs, feel like wearing sunglasses, the light became dark. But if the two pieces of polarizing film ideas together, it won’t be the same. When you rotate the two pieces of the relative Angle of the polarizing film, you will find that as the relative Angle is different, the brightness of the light will be more and darker. When two polaroids fence Angle perpendicular to each other, Light was completely failing. (see figure 8) and a liquid crystal display is to use this feature. Use upper and lower two pieces of fences between perpendicular slant plate, filled with liquid crystal, recycle electric field control liquid crystal rotation, to change the direction of light, so that different electric field sizes, can form different gray-scale brightness.

The upper and lower two layers of glass are mainly to grip the LCD with. Below the glass layer with Thin film transistor (thin film transistor, TFT screen), while the layer above the glass with a Color filter (Color filter). If you notice (see figure 3), these two pieces of glass are in contact with the side of the LCD screen, not smooth, but with jagged grooves. The main purpose of the groove with the hope of a long rod, liquid crystal molecules will line up along the grooves. In this way, Liquid crystal molecules are arranged neatly. Because if it is smooth and flat, the arrangement of the liquid crystal molecules will not neat, causing light scattering, forming a light-leaking phenomenon. In fact, this is just a theory that told us to put the glass and LCD interface, complete processing so that the arrangement of liquid crystal has a certain order. But in the actual manufacturing process, and can not be with such a groove, the distribution of glass is made usually in glass coating on the surface layer of the PI (polyimide), and then a cloth to do the action of friction (rubbing), In order to make the surface molecules of PI no longer be scattered and arranged in a fixed and uniform direction, this layer of PI is called the coordination membrane, and its function is just like the grooves in the glass in FIG. 3, which provides the interface conditions for the uniform arrangement of liquid crystal molecules and allows the liquid crystals to be arranged in a predetermined order.

We can know from figure 10, when there is no applied voltage between the upper and lower two pieces of glass, the arrangement of LCD will be in accordance with the match to the membrane of the upper and lower two pieces of glass. For TN type of LCD, and match to the film’s point of view of the poor to 90 degrees. (see figure 9) so the liquid crystal molecules are arranged by the up and down automatically rotate 90 degrees when the incident light passes through the upper polarizing film, the polarization of light waves will only order direction. Through the liquid crystal molecules, the liquid crystal molecules rotate for 90 degrees, so when the waves reach the lower polarizing film, the polarization direction of the light just turned 90 degrees. The polarizing film of the lower and upper polarizing film, 90 – degree Angle is just the differences. (see figure 9) so can smoothly through the light, but if we applied voltage between the upper and lower two pieces of glass, because the type TN LCD for the dielectric coefficient of different sex more positive type of LCD (epsilon / / > epsilon coming, represent the parallel direction of the dielectric coefficient is larger than the dielectric coefficient of the vertical direction, so when the liquid crystal molecules are influenced by an electric field, will tend to be parallel to the orientation of the electric field direction.), so we can see from figure 10, At this time, the polarized light wave passing through the upper polarizer will not change the polarization direction when passing through the liquid crystal molecule, so it cannot pass through the lower polarizer.

The so-called NW (Normally white), is to point to when we don’t apply voltage on the LCD screen panel, we can see the panel is pervious to light, also is bright, so-called Normally white. But on the other hand, when we don’t apply voltage on the LCD panel if the panel is not pervious to light, the look is black, it’s called NB (Normally black). We have just mentioned in figure 9 and figure 10 all belongs to the configuration of NW, also we can know from figure 11, For type TN LCD, located in the upper and lower glass is perpendicular to the membrane, and the difference between NB and NW just lies in the relative position of the polarizing film is different. For NB, the fluctuation of the polarizing film polarity is parallel to each other. So when the NB no applied voltage, the light will be because the polarity of the LCD to rotate 90 degrees to be pervious to light. Why there are NW and NB these two kinds of a different configuration of the polarizing film? Mainly for different applications. Commonly used in a desktop computer or notebook computer, most of the NW configuration. That’s because, if you notice, generally the use of computer software environment, you will find that most of the entire screen is a bright spot, that is to say, computer software for the application of white background and black text. Since on the point of the majority, using NW is more convenient, of course. Also because the NW window does not need to add the voltage, the average will compare to save electricity. In turn, said that the application of the NB environment mostly belongs to the screen for the application of black.

The STN LCD and TN LCD are very similar in structure, the main difference between TN LCD, the arrangement of the liquid crystal molecules, the rotation angle from top to bottom. A total of 90 degrees and type the STN LCD liquid crystal molecules are arranged, the rotation angle will be greater than 180 degrees, usually is 270 degrees. (see figure 12) because of its rotation Angle is different, its characteristics different. We from figure 13 TN type and type the STN LCD voltage of the transmittance curve can know, when the voltage is low, the light penetration rate is very high. With a high voltage, the light of the penetration rate is very low. So they belong to the Normal White polaroids configuration. When the voltage in the middle position, the change of type TN LCD curve is flat, and the change of the STN LCD type curve is steep. So in TN type LCD, when transmittance change from 90% to 10%, corresponding to the voltage difference is larger than the STN LCD. We mentioned before, in the liquid crystal display, The different characteristics of TN and STN will result in TN type LCD, which has more grayscale changes than STN type LCD, so generally TN type LCD has 6~8 bits of changes. It is 64 ~ 256 gray-scale changes. Type the STN LCD for a maximum of 4 bits are only 16 orders of gray-scale changes. In addition, the STN type and TN LCD has a different place is the reaction time (response time) general type the STN LCD it’s response time to type in more than 100 ms and TN LCD its response time is 30 ~ 50 ms as shown in the image change quickly for the STN LCD type ghosting effect phenomenon is easy to happen.

TFT LCD Chinese translation of the name is called a thin film transistor liquid crystal display, from the beginning, we mentioned LCD voltage control is needed to produce gray. And the use of a thin-film transistor to generate the voltage, to control the transition of liquid crystal display, is called a TFT LCD. From the point of the cross-section structure of figure 8, between upper and lower two layers of glass, with LCD, will form a parallel plate capacitor, we call it the CLC (capacitor of liquid crystal). Its size is about 0.1 m3, But on the practical application, the capacitance and unable to keep the voltage to the next time to update the data in the picture.

That is to say, when TFT is good to the capacitor charging power, it is impossible to maintain voltage, until the next TFT this point charge again. (in general of 60 Hz screen update frequency, need time to keep about 16 ms.) as a result, there were changes in voltage, displayed gray scale is not correct. Therefore generally on the design of the panel, we will add a storage capacitor CS (storage capacitor is about 0.5 pF). So charged electric voltage can keep until the next update screen. But the right, long on the glass TFT itself, just use a transistor to make the switch. Its main work is to determine the LCD source voltage on the driver whether to charge to this point. As for this point more charge to high voltage, so as to show how the gray-scale. It is outside of the LCD source driver.

If you have a chance, take a magnifying glass, close to the LCD screen. You will find that as shown in figure 9 shows. We know that red, blue and green, are the so-called primary colors. That is to say, using the three kinds of color, can produce a variety of different colors. In a lot of flat-panel displays, this principle is used to show the color. We put the RGB 3 kinds of color, is divided into independent three points, each has different gray-scale changes, then the three neighboring RGB display point, as the basic unit of a display, Pixel is that this a pixel, and can have different color changes. Then for a need for a 1024 * 768 resolution display screen, we just let the composition of the flat panel display with 1024 * 768 pixels, can show a picture of the right. In figure 9, each point between the Black part of RGB is called the Black matrix. We can find that looking back on it in figure 8Black matrix is mainly used to cover do not intend to previous to light part. Such as some ITOs walk the line, or Cr/Al walk the line or are part of a TFT. This is why we in figure 9, the highlight of each RGB, it seems, is not a rectangle, and also on the top left corner is a piece of black matrix cover part, this part of a black missing Angle is the location of the TFT.

Figure 9 shows the common arrangement of color filters. Stripe is most commonly used in OA products, such as laptops, desktop computers, etc. Why is stripe used in this application? More often than not, the reason is now software is the Windows interface. That is to say, we can see the screen content, is composed of a pile of boxes of various sizes. The strips, just can make the edge of the box, look more straight, and there won’t be a straight line, look have the feeling of burrs or serrated. But if it is applied in the AV products, just not the same. Probably because the TV signal is a character, the character of the line is not straight, the contour is a mostly irregular curve. So in the beginning, the Use Mosaic arrangement used in AV products is (Mosaic, or called arranged diagonally). But the latest AV products, more have been improved to use triangle arrangement (triangle, or known as the delta). In addition to the above arrangement, still have a kind of arrangement, which is called a square arrangement. It is not the same as the first few, it is not three-point to as a pixel, but with four points as a pixel. And just four points are combined to form a square.

The CRT screen, it is using a high-speed electron gun that emits electrons, hits the phosphors on the silver screen, so as to produce the light, to show the picture. LCD itself, however, can only control the brightness of the light through, no glowing function itself. Therefore, a liquid crystal display must be combined with a backplate, to provide high brightness, brightness, and uniform distribution of the light source. We can see in figure 14, of the backplate of the main parts are CCFL (cold cathode tube), reflex plate, guide plate, prism sheet, Diffuser plate, and so on. Tubes are the main light-emitting parts, by a light guide, everywhere. The light distribution and baffle will be limited only to the TFT LCD light direction. Finally, by prism sheet and help diffuser, the light evenly distributed to all areas, provide TFT LCD a bright light. While TFT LCD is borrowed by the rotation of the voltage-controlled liquid crystal, control through the brightness of the light, so as to form different grayscale.

Another box in figure 14 glue and spacer structure of two kinds of ingredients. The box adhesive USES is to make the LCD panel in the upper and lower two layers of glass, to be able to stick close and to provide a panel of LCD screen molecules, cut off from the outside world, so the box plastic as its name suggests, is around and around in the panel to the liquid crystal molecules box limited to within a panel. The spacer is mainly provided two-layer glass support, it must be distributed evenly on the glass, or a part but uneven distribution cause spacer gathered together, it will block the light, It is also unable to maintain the appropriate gap between the upper and lower glass, which will lead to uneven distribution of electric field and affect the performance of the crystal grayscale.

A very important specification of LCD is brightness, and the most important factor to determine the brightness is the opening rate. What is the opening rate? Is simple light can pass through the effective area proportion. 17, let’s look at the picture to the left of figure 17 is an LCD display from directly above or below the past structure. When the light is emitted through the backplate, not all of the light can be through the panel, like for LCD source driver chip and the gate driver chip signal line, and TFT itself, the stored voltage is the use of storage capacity, etc. These places besides incomplete pervious to light, but also because the light through these places is not under voltage control, to display the correct gray-scale, so have to use the black matrix to cover, in order to avoid interference to other correct brightness of the light area. So the effective area of the previous to light, it’s just like figure 17 shows area on the right. This piece of the effective area of the previous to light and the ratio of the total area is called the opening rate.

When the light is emitted from the backlight plate, it will pass through the polarizer, glass, LCD screen, color filter, etc. It is assumed that the penetration rate of each part is as follows:

Color filter:27%(assume that the material itself has a penetration rate of 80%, but since the filter itself is painted with color, only light waves of that color can be allowed to pass through. For RGB primary colors, only one of the three colors can be allowed to pass through. Therefore, only one-third of the brightness is left.

STONE is industrial screen manufacturers, provide a full range of 3.5 inches to 15.1 inches of small and medium-size standard quasi TFT LCD module, TFT screen module, TFT display module, display industry, industrial LCD screen, under the sunlight visually highlight TFT LCD display, industrial custom TFT screen, TFT LCD screen-wide temperature, industrial TFT LCD screen, touch screen industry. The TFT LCD module is very suitable forindustrial control equipment, medical instruments, POS system, electronic consumer products, vehicles, and other products.

The Panasonic Toughbook FZ-T1 is part of the latest fully-rugged handheld series from Panasonic and I know that when thinking about the toughest phones, most people will point to the Samsung Active series (or some other Chinese brands), but Toughbook devices are simply on another level in terms of ruggedness. I found it a bit amusing when Panasonic was referring to its 5-inch handsets as tablets that can make phone calls (which is not really wrong) and the Toughbook FZ-T1 is now a handheld and the Wi-Fi/4G version has all the functions of a normal smartphone. The way it is built and the additional features it has, clearly sets it apart even from the rest of the rugged smartphones and the closest device that I could find is the Cat S61 (due to its thermal imaging camera).

I held myself back for a while to include this product for more than a couple of reasons: it is unfortunately not suitable for the usual consumer and it’s specifically built for industry workers (mostly due to the integrated barcode scanner). That’s right, the Toughpad FZ-T1 features a thick case (which measures 3.0 x 6.1 x 0.7 inches including the barcode reader section – significantly slimmer than the N1 model), a fairly rounded back panel to keep the device comfortably in your hand and the black matte finish does help with the grip (so you don’t drop it). On the front of the device, just above the display, there’s a small battery indicator (when it’s red, the battery level is 10% or less), the ambient light/proximity sensors and the microphone.

Underneath the display, there is a mono speaker (can go up to 95dB) and a microphone – yes, the three physical buttons (Back, Start and Search) are now gone and replaced by the on-screen alternative. I think that all rugged smartphones should keep the physical buttons and not migrate towards a display-only approach, but I’m willing to give Panasonic a pass due to the glove mode (allows you to use the phone with thick gloves) and rain mode (makes sure that there are no misoperations if the display gets we – (the process involves limiting the touchscreen multi-touch usability from 10 fingers to just one finger).

The sides of the Toughbook FZ-T1 are a combination between the gray plastic that stretches towards the front bezels and a black rubberized material (this combo does help move the Toughbook FZ-T1 slightly outside the industrial look).

Furthermore, on the left side, a protective cover hides the microUSB port (there is no USB-C), on the top, there’s a 3.5mm headset jack which sits next to a 1D/2D barcode reader, while on the right, there’s the Power button, a programmable Side button and the volume buttons (on the bottom of the device, there is an expansion bus for attaching an optional cradle – useful in an industrial environment where you can easily misplace the device). The rear side of the FZ-T1 is quite interesting since there is a slightly inflated portion towards the top (to accommodate the barcode reader) with the camera embedded within it, while towards the bottom, there is a latch which, once operated, will expose the removable battery.

The large part of the front side is occupied by the 5-inch display, which has a resolution of 1280 x 720 pixels (a bit disconcerting for a 2-year old rugged phone), a pixel density of around 294ppi and up to 500cd/m2 brightness levels (seems to be the same as on the far older Toughpad FZ-E1). Yes, the display is outdated and I know that the focus was more towards functionality and less about entertainment, but even so it’s a bit ridiculous considering the price tag (the CAT S61 is also fairly industrial, but has a far batter display). That being said, the pixel density is low, the colors aren’t really as vibrant as what other cheaper phones from the competition have to offer and the viewing angles aren’t that great. Now, since this is a rugged device, it is expected that the screen won’t shatter easily and this is true for the most part since it can be dropped from 10 feet without taking any damage (the thick border that surrounds the display plays an important part) and it will survive without problems a lot of drops (yes, even face-first ones – it’s surprisingly difficult to destroy this device).

Furthermore, the Toughbook FZ-T1 is also MIL-STD-810G certified, so it can handle both high and low temperatures (the operating range is between -4 and 122 degrees Fahrenheit), explosive atmosphere, humidity, sand and dust, vibration (including loose cargo transportation), shock, freezing rain, acidic atmosphere and more. As expected, the Toughbook FZ-T1 is also waterproof and dust resistant, being both IP66 and IP68 rated, so you can submerge it down to 5 feet underwater for about 30 minutes. Inside the case, the Panasonic Toughbook FZ-T1 is equipped with a quad-core Qualcomm 210 MSM8909 chipset (the clock rate can go up to 1.1GHz), an integrated Adreno 304 graphics card, 2GB of RAM and 16GB of eMMC storage memory – you can add up to 64GB by using a microSD card. The device is also compatible with the following wireless and Voice&Data standards: IEEE802.11 a/b/g/n/d/h/i/r, Bluetooth, 4G LTE, HSPA+, UMTS, EDGE, GPRS and GSM. Seeing these specs, it does feel like Panasonic took a significant step backwards since the Qualcomm Snapdragon 210 MSM8909 is the entry-level SoC for Android smartphone, so the performance is not going to be that great (some resource-heavy apps are not going to work properly, but multi-tasking is decent due to the 2GB of RAM and especially thanks to the display resolution); the Adreno 304 paired with the 720p should be fine, but even so, most games will not run smoothly.

The ToughPad FZ-T1 uses Android 8.1 Oreo and it’s an interesting choice, considering that past devices from Panasonic relied on the Windows Mobile and it made sense since it had a better integration with various software from tech and industry companies. The Android OS is going to feel more comfortable for most users and I suppose this handheld rugged device doesn’t really need any special apps – as with other manufacturers of rugged smartphones, Panasonic doesn’t seem to like to update the OS on its devices.

The FZ-T1 is equipped with an 8-megapixel rear camera (with LED flash and auto-focus) and no, there is no front-facing camera on this smartphone (a bold decision, considering that even in an industrial environment, people may want to make video calls).

The rear camera will take reasonable photos in good lighting and especially outside in a sunny day (although there was a bit of overexposing), but indoors and during the night, the photos were blurry and full of noise. Overall, this is a tablet-level camera and won’t really satisfy if you want to use the phone as a main camera on holidays (not that anyone would want to do that) – it should be fine for scanning QR codes or for photographing schematics or other type of documents.

One of the most important aspects of any smartphone or tablet (rugged or not) is the battery life and truth be told, I was expecting a large battery, something similar to the Toughpad FZ-E1 (6200mAh), but no, the FZ-T1 has a 3,200mAh battery which is both replaceable and hot swappable. Panasonic claims that the battery can last up to 12 hours when scanning barcodes three times per minute (mixed with some light WiFi use and cellular calls). Furthermore, the Toughbook FZ-T1 should take about 2 hours and a half for charging the battery from 0 to 100% (depending on the ambient temperature, it can take more).

Verdict: Why isn’t the Panasonic Toughbook FZ-T1 the first in the list you may ask, since it’s such a great rugged device? Well, because it doesn’t really follow the same guidelines as the usual smartphones (or tablets, for that matter) and, while it’s true that rugged cell phones, in general, are more niche devices, the Panasonic Toughbook FZ-T1 is even more narrow into the targeted audience. To be more specific, this belongs in a warehouse with industrial workers and I highly doubt I’ll ever see an active person running with this mammoth strapped to their arm. That being said, the Panasonic Toughbook FZ-T1 is pretty much the pinnacle of ruggedness, having a screen resistant to shock, the case can handle pretty much everything you throw at it, it has some awesome features (suitable for an industrial environment), but there are some minuses, since software is a bit outdated, the camera is nothing to brag about (and the front-facing one is completely missing), the device is quite thick and the most important negative is the incredibly high price.

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“If you leave your phone in the car there’s the possibility that you can freeze the LCD in your phone, the liquid crystal,” said Joshua Watters, owner of Mr. Mustache Phone Repair.

He said for the most part, your phone or tablet will be just fine in the cold for a short period of time. After a few hours though things will start to go south.

“It can just get depleted and not take a charge anymore. It’s almost the same as it overheating if you leave it out in the sun in the summer time at over 140 degrees,” Watters said.

“If you’re outside shoveling just make sure you don’t get snow in your pockets with it. Your body heat will melt it and water and electronics is never good,” Watters said.

An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode,light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This organic layer is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, and portable systems such as smartphones and handheld game consoles. A major area of research is the development of white OLED devices for use in solid-state lighting applications.

There are two main families of OLED: those based on small molecules and those employing polymers. Adding mobile ions to an OLED creates a light-emitting electrochemical cell (LEC) which has a slightly different mode of operation. An OLED display can be driven with a passive-matrix (PMOLED) or active-matrix (AMOLED) control scheme. In the PMOLED scheme, each row and line in the display is controlled sequentially, one by one,thin-film transistor (TFT) backplane to directly access and switch each individual pixel on or off, allowing for higher resolution and larger display sizes.

OLED is fundamentally different from LED which is based on a p-n diode structure. In LEDs doping is used to create p- and n- regions by changing the conductivity of the host semiconductor. OLEDs do not employ a p-n structure. Doping of OLEDs is used to increase radiative efficiency by direct modification of the quantum-mechanical optical recombination rate. Doping is additionally used to determine the wavelength of photon emission.

An OLED display works without a backlight because it emits its own visible light. Thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD). In low ambient light conditions (such as a dark room), an OLED screen can achieve a higher contrast ratio than an LCD, regardless of whether the LCD uses cold cathode fluorescent lamps or an LED backlight. OLED displays are made in the same way as LCDs, but after TFT (for active matrix displays), addressable grid (for passive matrix displays) or indium-tin oxide (ITO) segment (for segment displays) formation, the display is coated with hole injection, transport and blocking layers, as well with electroluminescent material after the first 2 layers, after which ITO or metal may be applied again as a cathode and later the entire stack of materials is encapsulated. The TFT layer, addressable grid or ITO segments serve as or are connected to the anode, which may be made of ITO or metal.transparent displays being used in smartphones with optical fingerprint scanners and flexible displays being used in foldable smartphones.

André Bernanose and co-workers at the Nancy-Université in France made the first observations of electroluminescence in organic materials in the early 1950s. They applied high alternating voltages in air to materials such as acridine orange dye, either deposited on or dissolved in cellulose or cellophane thin films. The proposed mechanism was either direct excitation of the dye molecules or excitation of electrons.

In 1960, Martin Pope and some of his co-workers at New York University developed ohmic dark-injecting electrode contacts to organic crystals.work functions) for hole and electron injecting electrode contacts. These contacts are the basis of charge injection in all modern OLED devices. Pope"s group also first observed direct current (DC) electroluminescence under vacuum on a single pure crystal of anthracene and on anthracene crystals doped with tetracene in 1963volts. The proposed mechanism was field-accelerated electron excitation of molecular fluorescence.

Pope"s group reported in 1965exciton energy level. Also in 1965, Wolfgang Helfrich and W. G. Schneider of the National Research Council in Canada produced double injection recombination electroluminescence for the first time in an anthracene single crystal using hole and electron injecting electrodes,Dow Chemical researchers patented a method of preparing electroluminescent cells using high-voltage (500–1500 V) AC-driven (100–3000Hz) electrically insulated one millimetre thin layers of a melted phosphor consisting of ground anthracene powder, tetracene, and graphite powder.

The first Polymer LED (PLED) to be created was by Roger Partridge at the National Physical Laboratory in the United Kingdom. It used a film of poly(N-vinylcarbazole) up to 2.2 micrometers thick located between two charge-injecting electrodes. The light generated was readily visible in normal lighting conditions though the polymer used had 2 limitations; low conductivity and the difficulty of injecting electrons.

Research into polymer electroluminescence culminated in 1990, with J. H. Burroughes et al. at the Cavendish Laboratory at Cambridge University, UK, reporting a high-efficiency green light-emitting polymer-based device using 100nm thick films of poly(p-phenylene vinylene).plastic electronics and OLED research and device production grew rapidly.et al. at Yamagata University, Japan in 1995, achieved the commercialization of OLED-backlit displays and lighting.

In 1999, Kodak and Sanyo had entered into a partnership to jointly research, develop, and produce OLED displays. They announced the world"s first 2.4-inch active-matrix, full-color OLED display in September the same year.

Manufacturing of small molecule OLEDs was started in 1997 by Pioneer Corporation, followed by TDK in 2001 and Samsung-NEC Mobile Display (SNMD), which later became one of the world"s largest OLED display manufacturers - Samsung Display, in 2002.

The Sony XEL-1, released in 2007, was the first OLED television.Universal Display Corporation, one of the OLED materials companies, holds a number of patents concerning the commercialization of OLEDs that are used by major OLED manufacturers around the world.

On 5 December 2017, JOLED, the successor of Sony and Panasonic"s printable OLED business units, began the world"s first commercial shipment of inkjet-printed OLED panels.

A typical OLED is composed of a layer of organic materials situated between two electrodes, the anode and cathode, all deposited on a substrate. The organic molecules are electrically conductive as a result of delocalization of pi electrons caused by conjugation over part or all of the molecule. These materials have conductivity levels ranging from insulators to conductors, and are therefore considered organic semiconductors. The highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of organic semiconductors are analogous to the valence and conduction bands of inorganic semiconductors.

Originally, the most basic polymer OLEDs consisted of a single organic layer. One example was the first light-emitting device synthesised by J. H. Burroughes et al., which involved a single layer of poly(p-phenylene vinylene). However multilayer OLEDs can be fabricated with two or more layers in order to improve device efficiency. As well as conductive properties, different materials may be chosen to aid charge injection at electrodes by providing a more gradual electronic profile,quantum efficiency (up to 19%) by using a graded heterojunction.

During operation, a voltage is applied across the OLED such that the anode is positive with respect to the cathode. Anodes are picked based upon the quality of their optical transparency, electrical conductivity, and chemical stability.electrons flows through the device from cathode to anode, as electrons are injected into the LUMO of the organic layer at the cathode and withdrawn from the HOMO at the anode. This latter process may also be described as the injection of electron holes into the HOMO. Electrostatic forces bring the electrons and the holes towards each other and they recombine forming an exciton, a bound state of the electron and hole. This happens closer to the electron-transport layer part of the emissive layer, because in organic semiconductors holes are generally more mobile than electrons. The decay of this excited state results in a relaxation of the energy levels of the electron, accompanied by emission of radiation whose frequency is in the visible region. The frequency of this radiation depends on the band gap of the material, in this case the difference in energy between the HOMO and LUMO.

As electrons and holes are fermions with half integer spin, an exciton may either be in a singlet state or a triplet state depending on how the spins of the electron and hole have been combined. Statistically three triplet excitons will be formed for each singlet exciton. Decay from triplet states (phosphorescence) is spin forbidden, increasing the timescale of the transition and limiting the internal efficiency of fluorescent devices. Phosphorescent organic light-emitting diodes make use of spin–orbit interactions to facilitate intersystem crossing between singlet and triplet states, thus obtaining emission from both singlet and triplet states and improving the internal efficiency.

Indium tin oxide (ITO) is commonly used as the anode material. It is transparent to visible light and has a high work function which promotes injection of holes into the HOMO level of the organic layer. A second conductive (injection) layer is typically added, which may consist of PEDOT:PSS,barium and calcium are often used for the cathode as they have low work functions which promote injection of electrons into the LUMO of the organic layer.aluminium to avoid degradation. Two secondary benefits of the aluminum capping layer include robustness to electrical contacts and the back reflection of emitted light out to the transparent ITO layer.

Experimental research has proven that the properties of the anode, specifically the anode/hole transport layer (HTL) interface topography plays a major role in the efficiency, performance, and lifetime of organic light-emitting diodes. Imperfections in the surface of the anode decrease anode-organic film interface adhesion, increase electrical resistance, and allow for more frequent formation of non-emissive dark spots in the OLED material adversely affecting lifetime. Mechanisms to decrease anode roughness for ITO/glass substrates include the use of thin films and self-assembled monolayers. Also, alternative substrates and anode materials are being considered to increase OLED performance and lifetime. Possible examples include single crystal sapphire substrates treated with gold (Au) film anodes yielding lower work functions, operating voltages, electrical resistance values, and increasing lifetime of OLEDs.

Single carrier devices are typically used to study the kinetics and charge transport mechanisms of an organic material and can be useful when trying to study energy transfer processes. As current through the device is composed of only one type of charge carrier, either electrons or holes, recombination does not occur and no light is emitted. For example, electron only devices can be obtained by replacing ITO with a lower work function metal which increases the energy barrier of hole injection. Similarly, hole only devices can be made by using a cathode made solely of aluminium, resulting in an energy barrier too large for efficient electron injection.

Balanced charge injection and transfer are required to get high internal efficiency, pure emission of luminance layer without contaminated emission from charge transporting layers, and high stability. A common way to balance charge is optimizing the thickness of the charge transporting layers but is hard to control. Another way is using the exciplex. Exciplex formed between hole-transporting (p-type) and electron-transporting (n-type) side chains to localize electron-hole pairs. Energy is then transferred to luminophore and provide high efficiency. An example of using exciplex is grafting Oxadiazole and carbazole side units in red diketopyrrolopyrrole-doped Copolymer main chain shows improved external quantum efficiency and color purity in no optimized OLED.

Organic small-molecule electroluminescent materials have the advantages of a wide variety, easy to purify, and strong chemical modifications. In order to make the luminescent materials to emit light as required, some chromophores or unsaturated groups such as alkene bonds and benzene rings will usually be introduced in the molecular structure design to change the size of the conjugation range of the material, so that the photophysical properties of the material changes. In general, the larger the range of π-electron conjugation system, the longer the wavelength of light emitted by the material. For instance, with the increase of the number of benzene rings, the fluorescence emission peak of benzene, naphthalene, anthracene,anthracenes, biphenyl acetylene aryl derivatives, coumarin derivatives,Ching W. Tang et al.Eastman Kodak. The term OLED traditionally refers specifically to this type of device, though the term SM-OLED is also in use.

Molecules commonly used in OLEDs include organometallic chelates (for example Alq3, used in the organic light-emitting device reported by Tang et al.), fluorescent and phosphorescent dyes and conjugated dendrimers. A number of materials are used for their charge transport properties, for example triphenylamine and derivatives are commonly used as materials for hole transport layers.perylene, rubrene and quinacridone derivatives are often used.3 has been used as a green emitter, electron transport material and as a host for yellow and red emitting dyes.

Because of the structural flexibility of small-molecule electroluminescent materials, thin films can be prepared by vacuum vapor deposition, which is more expensive and of limited use for large-area devices. The vacuum coating system, however, can make the entire process from film growth to OLED device preparation in a controlled and complete operating environment, helping to obtain uniform and stable films, thus ensuring the final fabrication of high-performance OLED devices.However, small molecule organic dyes are prone to fluorescence quenching

Polymer light-emitting diodes (PLED, P-OLED), also light-emitting polymers (LEP), involve an electroluminescent conductive polymer that emits light when connected to an external voltage. They are used as a thin film for full-spectrum colour displays. Polymer OLEDs are quite efficient and require a relatively small amount of power for the amount of light produced.

Vacuum deposition is not a suitable method for forming thin films of polymers. If the polymeric OLED films are made by vacuum vapor deposition, the chain elements will be cut off and the original photophysical properties will be compromised. However, polymers can be processed in solution, and spin coating is a common method of depositing thin polymer films. This method is more suited to forming large-area films than thermal evaporation. No vacuum is required, and the emissive materials can also be applied on the substrate by a technique derived from commercial inkjet printing.Langmuir-Blodgett film.

Typical polymers used in PLED displays include derivatives of poly(p-phenylene vinylene) and polyfluorene. Substitution of side chains onto the polymer backbone may determine the colour of emitted lightring opening metathesis polymerization.

Phosphorescent organic light-emitting diodes use the principle of electrophosphorescence to convert electrical energy in an OLED into light in a highly efficient manner,

Typically, a polymer such as poly(N-vinylcarbazole) is used as a host material to which an organometallic complex is added as a dopant. Iridium complexes3

The heavy metal atom at the centre of these complexes exhibits strong spin-orbit coupling, facilitating intersystem crossing between singlet and triplet states. By using these phosphorescent materials, both singlet and triplet excitons will be able to decay radiatively, hence improving the internal quantum efficiency of the device compared to a standard OLED where only the singlet states will contribute to emission of light.

Applications of OLEDs in solid state lighting require the achievement of high brightness with good CIE coordinates (for white emission). The use of macromolecular species like polyhedral oligomeric silsesquioxanes (POSS) in conjunction with the use of phosphorescent species such as Ir for printed OLEDs have exhibited brightnesses as high as 10,000cd/m2.

a) Bottom-emitting and b) top-emitting OLED structures; c,d) Schematic diagrams based on bottom-emitting and top-emitting OLEDs with low and high contrast ratio, respectively.

The bottom-emission organic light-emitting diode (BE-OLED) is the architecture that was used in the early-stage AMOLED displays. It had a transparent anode fabricated on a glass substrate, and a shiny reflective cathode. Light is emitted from the transparent anode direction. To reflect all the light towards the anode direction, a relatively thick metal cathode such as aluminum is used. For the anode, high-transparency indium tin oxide (ITO) was a typical choice to emit as much light as possible.thin film transistor (TFT) substrate, and the area from which light can be extracted is limited and the light emission efficiency is reduced.

An alternative configuration is to switch the mode of emission. A reflective anode, and a transparent (or more often semi-transparent) cathode are used so that the light emits from the cathode side, and this configuration is called top-emission OLED (TE-OLED). Unlike BEOLEDs where the anode is made of transparent conductive ITO, this time the cathode needs to be transparent, and the ITO material is not an ideal choice for the cathode because of a damage issue due to the sputtering process.transmittance and high conductivity.

When light waves meet while traveling along the same medium, wave interference occurs. This interference can be constructive or destructive. It is sometimes desirable for several waves of the same frequency to sum up into a wave with higher amplitudes.

Since both electrodes are reflective in TEOLED, light reflections can happen within the diode, and they cause more complex interferences than those in BEOLEDs. In addition to the two-beam interference, there exists a multi-resonance interference between two electrodes. Because the structure of TEOLEDs is similar to that of the Fabry-Perot resonator or laser resonator, which contains two parallel mirrors comparable to the two reflective electrodes),

In the case of OLED, that means the cavity in a TEOLED could be especially designed to enh