tft display vs led free sample
In market, LCD means passive matrix LCDs which increase TN (Twisted Nematic), STN (Super Twisted Nematic), or FSTN (Film Compensated STN) LCD Displays. It is a kind of earliest and lowest cost display technology.
LCD screens are still found in the market of low cost watches, calculators, clocks, utility meters etc. because of its advantages of low cost, fast response time (speed), wide temperature range, low power consumption, sunlight readable with transflective or reflective polarizers etc. Most of them are monochrome LCD display and belong to passive-matrix LCDs.
TFT LCDs have capacitors and transistors. These are the two elements that play a key part in ensuring that the TFT display monitor functions by using a very small amount of energy without running out of operation.
Normally, we say TFT LCD panels or TFT screens, we mean they are TN (Twisted Nematic) Type TFT displays or TN panels, or TN screen technology. TFT is active-matrix LCDs, it is a kind of LCD technologies.
TFT has wider viewing angles, better contrast ratio than TN displays. TFT display technologies have been widely used for computer monitors, laptops, medical monitors, industrial monitors, ATM, point of sales etc.
Actually, IPS technology is a kind of TFT display with thin film transistors for individual pixels. But IPS displays have superior high contrast, wide viewing angle, color reproduction, image quality etc. IPS screens have been found in high-end applications, like Apple iPhones, iPads, Samsung mobile phones, more expensive LCD monitors etc.
Both TFT LCD displays and IPS LCD displays are active matrix displays, neither of them can produce color, there is a layer of RGB (red, green, blue) color filter in each LCD pixels to make LCD showing colors. If you use a magnifier to see your monitor, you will see RGB color. With switch on/off and different level of brightness RGB, we can get many colors.
Neither of them can’t release color themselves, they have relied on extra light source in order to display. LED backlights are usually be together with them in the display modules as the light sources. Besides, both TFT screens and IPS screens are transmissive, it will need more power or more expensive than passive matrix LCD screens to be seen under sunlight. IPS screens transmittance is lower than TFT screens, more power is needed for IPS LCD display.
Confused about LED vs. LCD vs. TFT? Here"s everything you need to know. Creating or upgrading a device display or screen can involve a lot of different things, but it often comes down to one major question - what kind of display should you get?
So, there are 3 common displays LED, LCD and TFT available in the market. All terms refer to the flat-panel display, or screen, of a computer monitor or television set. In this article, we are going to differentiate between them. It will help you to choose a better one.
LCD stands for liquid crystal display. Works by adjusting the amount of light blocked. Usually has a backlight but might not (clocks, calculators, Nintendo Gameboy). The green-black ones can be very cheap and are a mature technology. Response time can be slow. An LCD display uses the light balancing qualities of crystals. Today LCDs are used in a great number of products and applications. Your TV, computer screen, calculator, cell phone and the dreaded alarm clock are all made of an LCD flat panel. Color LCDs produce the color based on two techniques: Passive matrix and active matrix. Passive matrix is the cheapest technology of the two. The other technology is called an active matrix or TFT. Active matrix displays produce really sharp and clear images.
This is a type of LCD with a thin film transistor attached to each pixel. All computer LCD screens are TFT since the early 2000s; older ones had slower response times and poorer color. Cost is now very good; power consumption is fairly good but dominated by the backlight. Has to be manufactured out of glass. The TFT layer is embedded in the screen itself, it reduces crosstalk between pixels. Crosstalk happens when a signal sends to a pixel also affects the pixel next to it. This makes the TFT technology the technology offering the best resolution and image quality. It also makes it a bit more expensive. Today TFTs have become the standard when producing LCD screens.
LED stands for a light emitting diode. As the name suggests, emits light rather than blocking it like LCD. Used for red/green/blue/white indicator lights everywhere. Some manufacturers advertise "LED" displays that are TFT screens with a white LED backlight, which is just confusing. Ones that are real LED screens are usually OLED.
Some devices actually have backlights made from Red, Green and Blue LEDs, normally referred to as RGB LED, which tend to have better color reproduction than any other display.
LED screen is just like saying that it is a plastic screen. You still have the WHOLE screen illuminated all the time and LED is "good" only for being more eco-friendly and probably more bright at max setting if you ever need this.
An LCD panel is, in fact, 2 layers of glass with some volume of Liquid Crystal in between. These two form the panel itself. The 2 layers are usually called Color Filter Glass (above) and TFT glass (below).
A standard TFT has a whole "lamp" behind it, illuminating the whole screen all the time. This way, you cannot have a true black, as it is still illuminated and stay grayish.
TFTs are a type of active matrix display that controls individual pixel updates several times per second on the screen to update the image relative to the content source.
TFT displays use more electricity than regular LCD screens, so they not only cost more in the first place, but they are also more expensive to operate.
LCDs use fluorescent lights while LEDs use those light emitting diodes. The fluorescent lights in an LCD are always behind the screen. On an LED, the light emitting diodes can be placed either behind the screen or around its edges.
TFT is an abbreviation for Thin Film Transistor, a flat panel display used to improve the operation and utility of LCD screens. In order to portray an appearance to the audience, a liquid crystal display (LCD) utilizes a crystalline-filled fluid to modify rear lighting polarized origin through the use of an electromagnetic force among two relatively thin metal wires such as indium oxide (ITO). However, color TFT displays are associated with this method, which can be employed in both divided and pixelated display systems.
With motion pictures displayed on an LCD, the intrinsic sluggish rate of increase between liquid phases over a significant number of pixel components can be an issue due to capacitance impacts, which can create a blurring of the visuals. Placing a high-velocity LCD control device inside the formation of a thin-film transistor immediately next to the cell component just on a glass screen, the issue of LCD picture speed may be substantially improved, and image blur can be eliminated for all useful purposes entirely.
Organic light-emitting diodes (AMOLEDs) are a type of flat light-emitting advanced technologies that are created by interspersing a succession of organic thin sheets over two conducting conductors. An electrical charge causes a brilliant light to be produced when the current flows. AMOLED displays are light-emitting screens that do not require a backlight, making them thinner and more energy-efficient than liquid crystal displays (LCDs) (which will need a white backlight).
AMOLED displays are not only thin and fuel-intensive, but they also deliver the highest image quality available, so they can be made translucent, elastic, bendable, or even rollable and stretchy in the future, allowing for a variety of applications. AMOLEDs are a revolutionary technology in terms of display devices! It is possible to create an AMOLED by sandwiching a sequence of thin films across phase conductors. Electric charge causes a brilliant light to be emitted when the current flows through the coil.
The color display is fantastic. Color intensity, sharpness, and luminance settings that are second to none and can be customized to meet the needs of any application.
Half-Life has been expanded. TFT displays have a far longer half-life than its LED equivalents, and they are available in a number of sizes, which might have an effect on the device"s half-life based on the phone"s usage as well as other variables. Touch panels for TFT screens can be either resistant or capacitance in nature.
Due to the apparent glass panels, there is limited functionality. For instance, there are ineffective for outdoor use because the glass can display glares from its natural lighting)
They rely on backlight to give illumination rather than generating their own light. Hence they require constructed light-creating diodes (LEDs) in their backlit display framework to ensure enough brightness.
Backlighting is unnecessary for AMOLEDs. LCDs produce images by selectively blocking parts of the illumination, whereas AMOLEDs produce light. AMOLEDs utilize less energy than LCDs since they don"t need backlighting. This is critical for battery-powered devices such as phones.
While AMOLED light-emitting sheets are lightweight, the substrate can also be elastic rather than stiff. AMOLED films are not limited to glass-like LEDs and LCDs.
AMOLEDs offer 170-degree ranges of vision. LCDs operate by obscuring the light. Hence they have intrinsic viewing obstacles. In addition, AMOLEDs have a substantially wider viewing spectrum.
AMOLEDs outperform LEDs. Since AMOLED organic coatings are less than LED inorganic crystal levels, AMOLED conducting and particle emitters layers can just be multi-layered. Also, LEDs and LCDs need glass backing, which absorbs light. AMOLEDs don"t need it.
AMOLEDs seem to be simpler to implement and larger. AMOLEDs are constructed of polymers and may be produced into big sheets. It takes a lot of extra liquid crystals to build and set down.
While red and green AMOLED sheets have a greater lifespan (46,000 to 230,000 hours), azure compounds have significantly shorter longevity (up to roughly 14,000 hours).
Due to the fact that AMOLED displays inherently emit illumination, they do not need a backlight when used on a monitor screen. Conversely, LCDs require backlights since the liquid crystals themselves are incapable of producing light under their own. Direct light emission from AMOLED displays also allows for the developing of lightweight display devices than others using TFT LCDs.
LCD displays have a higher brightness than AMOLED panels. This is owing to the LCD"s usage of led backlight, which may provide a brilliant illumination of the entire display. Despite the fact that AMOLEDs produce high levels of brilliance from their illumination, they will never be able to match the intensity of LCD lighting.
LCD screens use less power than AMOLED displays, which provides a slight advantage. The amount of energy consumed by AMOLED displays is dependent on the intensity of the screen. Lowered luminance results in lower energy usage, however, it might not be the best solution because the contrast would suffer as a result of the decreased brightness. In some situations, such as when to use an AMOLED device in direct sunlight, it is not an optimal situation.
However, the backlit keys of TFT displays account for the majority of their power usage. TFT screens" efficiency is considerably improved when the backlight is set to a lesser brightness level than the default setting. For example, replacing the light of an LCD TV with just an Led flash will have no effect on the image quality, but will result in lower power usage than replacing the light of an AMOLED TV.
With the exception of phones, numerous other technologies make use of displays to allow customers to engage in direct communication with them. To determine whether or not TFT LCD will be able to withstand the development of AMOLED innovation, we should first review the benefits of LCD technology. The backlighting quality ensures that whites are strong and brightness is superb but will deplete a battery much more quickly than just an AMOLED display. Furthermore, the cost of LCD screens is a considerable consideration. In addition to being less expensive and more easily accessible, they are produced in standard industry sizes, allowing them to be purchased for innovative products with relative ease.
TFT displays are also known as an “Active Matrix TFT LCD module” and have an array of thin film transistors fabricated on the glass that makes the LCD. There is one of these transistors for each pixel on the LCD.
LCDs use voltage applied to a field of microscopic liquid crystals to change the crystal’s orientation, which in turn changes the polarization of the liquid crystal which creates light or dark pixels on the display.
These pixels are arranged to create characters or graphic images. This type of display may be sunlight-readable and may have a backlight, which allows it to be viewed in dark areas.
Beautiful, complex images: All of our TFT modules are full-color graphic displays. Unlike standard monochrome character displays, you can create complex images for an imaginative user experience.
Thin and light: These are ideal display modules for handheld devices, communications equipment, information displays, and test and measurement equipment.
Single Supply: Most of the TFTs use an integrated controller with built-in voltage generation so only a single 3.3v supply is needed for both the panel power and logic voltage.
Many of the LCD controllers on board our graphic LCD display modules also include a CGROM (character generator ROM) which allows for easy character information as well as full bit-mapped graphic information to be shown.
Some of the graphic LCD displays have the ability to render graphics in grayscale, enabling you to show images and elements of your UI (user interface) with more depth and definition.
Because OLEDs are emissive, these displays can always be used in dark environments. There is usually a software command or hardware setting that will allow OLEDs to be dimmed.
Some OLED displays are bright enough to be sunlight readable–these models will typically take more current and may have a shorter rated lifetime. Additionally, OLEDs have extremely wide viewing angles.
What makes OLEDs useful for display construction is that they can be fabricated in bulk. Using OLED fabrication techniques, all the diodes can be made at the same time, at a much lower cost. OLEDs also come in a wide variety of colors.
For years, TFT displays have been the dominating technology in visualization. TFT LCD displays are everywhere in our daily lives; in consumer electronics, health care, communication devices and industry applications. While there are many LCD products in the market, they are not always suitable for every application. This is especially true for industrial TFT LCD. Understanding different requirements between industrial display and consumer TFT LCD, will help determine the best TFT LCD for your application.
Consumer grade TFT LCD like cell phone screen and computer monitor occupy big chunk of LCD market. Due to the nature of consumer market, competitive pricing and quick production cycles, these TFT LCDs are lack of the durability that industrial LCD has. Not like our cell phone screen and computer monitor, industrial LCD displays are used in much challenging environments. For example, an TFT LCD display on production line will face constant vibration, high working temperature. Its endurance to outside condition is a must.
Industrial TFT LCD has very good visibility. Which includes wide viewing angle, so that staff on production line can easily read information from different angles.
Sunlight readable is another important aspect that industrial TFT LCD persists. Many industrial applications are used outdoor, under direct sunlight. And user needs to be able to read what is on LCD screen easily. Topway has years experience on producing sunlight readable TFT LCD by using high brightness LED backlight and low reflectance technologies.
Industrial TFT LCD is made with high quality industrial grade components and material. Only then we could produce high quality TFT display that survives rigid tests like ESD, EMI and aging test, etc. All LCD product from Topway went through strict testings before reaching customers" warehouses.
Industrial TFT LCD has way longer supply commitment than consumer LCD. Ever try to fix a 2~3 years old cell phone"s crack screen? It is very difficult and expensive. Because replacement LCD screen is no longer being made. On the other hand, industrial LCD screen usually is in production for 10 plus years. And most of the time, for Topway anyway, there will be an upgrade model to replace end-of-life product. Thus, our customers won"t need to do much change on their product.
Industrial TFT LCD is a lot better in many areas than consumer one, even they look similar in normal situation. Topway as an industrial TFT LCD manufacturer, has been designing and producing industry grade LCD for more than twenty years. Our commitment on quality and customer service wins Topway friendship and orders. Please feel free to leave us message on your next industry project.
Let us start with the basics first; refresh the knowledge about TN and LCD displays in general, later we will talk about TFTs (Thin Film Transistors), how they differ from regular monochrome LCD displays. Then we will go on to the ghosting effect, so we will not only discuss the technology behind the construction of the TFT, but also some phenomena, like the ghosting effect, or grayscale inversion, that are important to understand when using an LCD TFT display.
Next, we will look at different technologies of the TFT LCD displays like TN, IPS, VA, and of course about transmissive and transflective LCD displays, because TFT displays also can be transmissive and transflective. In the last part we will talk about backlight.
Let us start with a short review of the most basic liquid crystal cell, which is the TN (twisted nematic) display. On the picture above, we can see that the light can be transmit through the cell or blocked by the liquid crystal cell using voltage. If you want to learn more about monochrome LCD displays and the basics of LCD displays, follow this link.
What is a TFT LCD display and how it is different from a monochrome LCD display? TFT is called an active display. Active, means we have one or more transistors in every cell, in every pixel and in every subpixel. TFT stands for Thin Film Transistor, transistors that are very small and very thin and are built into the pixel, so they are not somewhere outside in a controller, but they are in the pixel itself. For example, in a 55-inch TV set, the TFT display contains millions of transistors in the pixels. We do not see them, because they are very small and hidden, if we zoom in, however, we can see them in every corner of each pixel, like on the picture below.
On the picture above we can see subpixels, that are basic RGB (Red, Green, Blue) colors and a black part, with the transistors and electronic circuits. We just need to know that we have pixels, and subpixels, and each subpixel has transistors. This makes the display active, and thus is called the TFT display. TFT displays are usually color displays, but there are also monochrome TFT displays, that are active, and have transistors, but have no colors. The colors in the TFT LCD display are typically added by color filters on each subpixel. Usually the filters are RGB, but we also have RGBW (Red, Green, Blue, White) LCD displays with added subpixels without the filter (White) to make the display brighter.
Going a little bit deeper, into the TFT cell, there is a part inside well known to us from the monochrome LCD display Riverdi University lecture. We have a cell, liquid crystal, polarizers, an ITO (Indium Tin Oxide) layer for the electrodes, and additionally an electronic circuit. Usually, the electronic circuit consists of one transistor and some capacitors to sustain the pixel state when we switch the pixel OFF and ON. In a TFT LCD display the pixels are much more complicated because apart from building the liquid crystal part, we also need to build an electronic part.
That is why TFT LCD display technologies are very expensive to manufacture. If you are familiar with electronics, you know that the transistor is a kind of switch, and it allows us to switch the pixel ON and OFF. Because it is built into the pixel itself, it can be done very quickly and be very well controlled. We can control the exact state of every pixel not only the ON and OFF states, but also all the states in between. We can switch the light of the cells ON and OFF in several steps. Usually for TFT LCD displays it will be 8-bit steps per color, so we have 256 steps of brightness for every color, and every subpixel. Because we have three subpixels, we have a 24-bit color range, that means over 16 million combinations, we can, at least theoretically, show on our TFT LCD display over 16 million distinct colors using RGB pixels.
Now that we know how the TFT LCD display works, we can now learn some practical things one of which is LCD TFT ghosting. We know how the image is created, but what happens when we have the image on the screen for a prolonged time, and how to prevent it. In LCD displays we have something called LCD ghosting. We do not see it very often, but in some displays this phenomenon still exists.
If some elements of the picture i.e., your company logo is in the same place of the screen for a long period of time, for couple of weeks, months or a year, the crystals will memorize the state and later, when we change the image, we may see some ghosting of those elements. It really depends on many conditions like temperature and even the screen image that we display on the screen for longer periods of time. When you build your application, you can use some techniques to avoid it, like very rapid contrast change and of course to avoid the positioning the same image in the same position for a longer time.
You may have seen this phenomenon already as it is common in every display technology, and even companies like Apple put information on their websites, that users may encounter this phenomenon and how to fix it. It is called image ghosting or image persistence, and even Retina displays are not free of it.
Another issue present in TFT displays, especially TN LCD displays, is grayscale inversion. This is a phenomenon that changes the colors of the screen according to the viewing angle, and it is only one-sided. When buying a TFT LCD display, first we need to check what kind of technology it is. If it is an IPS display, like the Riverdi IPS display line, then we do not need to worry about the grayscale inversion because all the viewing angles will be the same and all of them will be very high, like 80, 85, or 89 degrees. But if you buy a more common or older display technology type, like the TN (twisted nematic) display, you need to think where it will be used, because one viewing angle will be out. It may be sometimes confusing, and you need to be careful as most factories define viewing direction of the screen and mistake this with the greyscale inversion side.
On the picture above, you can see further explanation of the grayscale inversion from Wikipedia. It says that some early panels and also nowadays TN displays, have grayscale inversion not necessary up-down, but it can be any angle, you need to check in the datasheet. The reason technologies like IPS (In-Plane Switching), used in the latest Riverdi displays, or VA, were developed, was to avoid this phenomenon. Also, we do not want to brag, but the Wikipedia definition references our website.
We know already that TN (twisted nematic) displays, suffer from grayscale inversion, which means the display has one viewing side, where the image color suddenly changes. It is tricky, and you need to be careful. On the picture above there is a part of the LCD TFT specification of a TN (twisted nematic) display, that has grayscale inversion, and if we go to this table, we can see the viewing angles. They are defined at 70, 70, 60 and 70 degrees, that is the maximum viewing angle, at which the user can see the image. Normally we may think that 70 degrees is better, so we will choose left and right side to be 70 degrees, and then up and down, and if we do not know the grayscale inversion phenomena, we may put our user on the bottom side which is also 70 degrees. The viewing direction will be then like a 6 o’clock direction, so we call it a 6 o’clock display. But you need to be careful! Looking at the specification, we can see that this display was defined as a 12 o’clock display, so it is best for it to be seen from a 12 o’clock direction. But we can find that the 12 o’clock has a lower viewing angle – 60 degrees. What does it mean? It means that on this side there will be no grayscale inversion. If we go to 40, 50, 60 degrees and even a little bit more, probably we will still see the image properly. Maybe with lower contrast, but the colors will not change. If we go from the bottom, from a 6 o’clock direction where we have the grayscale inversion, after 70 degrees or lower we will see a sudden color change, and of course this is something we want to avoid.
To summarize, when you buy older technology like TN and displays, which are still very popular, and Riverdi is selling them as well, you need to be careful where you put your display. If it is a handheld device, you will see the display from the bottom, but if you put it on a wall, you will see the display from the top, so you need to define it during the design phase, because later it is usually impossible or expensive to change the direction.
We will talk now about the other TFT technologies, that allow us to have wider viewing angles and more vivid colors. The most basic technology for monochrome and TFT LCD displays is twisted nematic (TN). As we already know, this kind of displays have a problem with grayscale inversion. On one side we have a higher retardation and will not get a clear image. That is why we have other technologies like VA (Vertical Alignment), where the liquid crystal is differently organized, and another variation of the TFT technology – IPS which is In-Plane Switching. The VA and IPS LCD displays do not have a problem with the viewing angles, you can see a clear image from all sides.
Apart from the different organization of the liquid crystals, we also organize subpixels a little bit differently in a VA and IPS LCD displays. When we look closer at the TN display, we will just see the subpixels with color filters. If we look at the VA or IPS display they will have subpixels of subpixels. The subpixels are divided into smaller parts. In this way we can achieve even wider viewing angles and better colors for the user, but of course, it is more complicated and more expensive to do.
The picture above presents the TN display and grayscale inversion. For IPS or VA technology there is no such effect. The picture will be the same from all the sides we look so these technologies are popular where we need wide viewing angles, and TN is popular where we don’t need that, like in monitors. Other advantages of IPS LCD displays are they give accurate colors, and wide viewing angles. What is also important in practice, in our projects, is that the IPS LCD displays are less susceptible to mechanical force. When we apply mechanical force to the screen, and have an optically bonded touch screen, we push the display as well as squeeze the cells. When we have a TN display, every push on the cell changes the image suddenly, with the IPS LCD displays with in-plane switching, different liquid crystals organization, this effect is lesser. It is not completely removed but it is much less distinct. That is another reason IPS displays are very popular for smartphones, tablets, when we have the touchscreens usually optically bonded.
If we wanted to talk about disadvantages, there is a question mark over it, as some of them may be true, some of them do not rely on real cases, what kind of display, what kind of technology is it. Sometimes the IPS displays can have higher power consumption than others, in many cases however, not. They can be more expensive, but not necessarily. The new IPS panels can cost like TN panels, but IPS panels definitely have a longer response time. Again, it is not a rule, you can make IPS panels that are very fast, faster than TN panels, but if you want the fastest possible display, probably the TN panel will be the fastest. That is why the TN technology is still popular on the gaming market. Of course, you can find a lot of discussions on the internet, which technology is better, but it really depends on what you want to achieve.
Now, let us look at the backlight types. As we see here, on the picture above, we have four distinct types of backlight possible. The most common, 95 or 99 per cent of the TFT LCD displays on the market are the transmissive LCD display type, where we need the backlight from the back. If you remember from our Monochrome LCD Displays lecture, for transmissive LCD displays you need the backlight to be always on. If you switch the backlight off, you will not see anything. The same as for monochrome LCD displays, but less popular for TFT displays, we have the transflective LCD display type. They are not popular because usually for transflective TFT displays, the colors lack in brightness, and the displays are not very practical to use. You can see the screen, but the application is limited. Some transflective LCD displays are used by military, in applications where power consumption is paramount; where you can switch the backlight off and you agree to have lower image quality but still see the image. Power consumption and saving energy is most important in some kind of applications and you can use transflective LCD displays there. The reflective type of LCD displays are almost never used in TFT. There is one technology called Low Power Reflective Displays (LPRD) that is used in TFT but it is not popular. Lastly, we have a variation of reflective displays with frontlight, where we add frontlight to the reflective display and have the image even without external light.
Just a few words about Low Power Reflective Displays (LPRD). This kind of display uses environmental light, ambient light to reflect, and produce some colors. The colors are not perfect, not perfectly clear, but this technology is becoming increasingly popular because it allows to have color displays in battery powered applications. For example, a smartwatch would be a case for that technology, or an electrical bike or scooter, where we can not only have a standard monochrome LCD display but also a TFT LCD color display without the backlight; we can see the image even in
strong sunlight and not need backlight at all. So, this kind of TFL LCD display technology is getting more and more popular when we have outdoor LCD displays and need a low power consumption.
On the picture above, we have some examples of how transmissive and reflective LCD displays work in the sunlight. If we have a simple image, like a black and white pattern, then on a transmissive LCD display, even with 1000 candela brightness, the image probably will be lower quality than for a reflective LCD display; if we have sunlight, we have very strong light reflections on the surface of the screen. We have talked about contrast in more detail in the lecture Sunlight Readable Displays. So, reflective LCD displays are a better solution for outdoor applications than transmissive LCD displays, where you need a really strong backlight, 1000 candela or more, to be really seen outdoors.
To show you how the backlight of LCD displays is built, we took the picture above. You can see the edge backlight there, where we have LEDs here on the small PCB on the edge, and we have a diffuser that distributes the light to the whole surface of LCD screen.
In addition to the backlight, we have something that is called a frontlight. It is similar to backlight, it also uses the LEDs to put the light into it, but the frontlight needs to be transparent as we have the display behind. On the example on the picture above we can see an e-paper display. The e-paper display is also a TFT display variation, but it is not LCD (liquid crystal), it is a different technology, but the back of the display is the same and it is reflective. The example you see is the Kindle 4 eBook reader. It uses an e-paper display and a frontlight as well, so you can read eBooks even during the night.
The ST7789 TFT module contains a display controller with the same name: ST7789. It’s a color display that uses SPI interface protocol and requires 3, 4 or 5 control pins, it’s low cost and easy to use. This display is an IPS display, it comes in different sizes (1.3″, 1.54″ …) but all of them should have the same resolution of 240×240 pixel, this means it has 57600 pixels. This module works with 3.3V only and it doesn’t support 5V (not 5V tolerant).
The ST7789 display module shown in project circuit diagram has 7 pins: (from right to left): GND (ground), VCC, SCL (serial clock), SDA (serial data), RES (reset), DC (or D/C: data/command) and BLK (back light).
As mentioned above, the ST7789 TFT display controller works with 3.3V only (power supply and control lines). The display module is supplied with 3.3V (between VCC and GND) which comes from the Arduino board.
To connect the Arduino to the display module, I used voltage divider for each line which means there are 4 voltage dividers. Each voltage divider consists of 2.2k and 3.3k resistors, this drops the 5V into 3V which is sufficient.
The first library is a driver for the ST7789 TFT display which can be installed from Arduino IDE library manager (Sketch —> Include Library —> Manage Libraries …, in the search box write “st7789” and install the one from Adafruit).
In this guide we’re going to show you how you can use the 1.8 TFT display with the Arduino. You’ll learn how to wire the display, write text, draw shapes and display images on the screen.
The 1.8 TFT is a colorful display with 128 x 160 color pixels. The display can load images from an SD card – it has an SD card slot at the back. The following figure shows the screen front and back view.
This module uses SPI communication – see the wiring below . To control the display we’ll use the TFT library, which is already included with Arduino IDE 1.0.5 and later.
The TFT display communicates with the Arduino via SPI communication, so you need to include the SPI library on your code. We also use the TFT library to write and draw on the display.
In which “Hello, World!” is the text you want to display and the (x, y) coordinate is the location where you want to start display text on the screen.
The 1.8 TFT display can load images from the SD card. To read from the SD card you use the SD library, already included in the Arduino IDE software. Follow the next steps to display an image on the display:
Note: some people find issues with this display when trying to read from the SD card. We don’t know why that happens. In fact, we tested a couple of times and it worked well, and then, when we were about to record to show you the final result, the display didn’t recognized the SD card anymore – we’re not sure if it’s a problem with the SD card holder that doesn’t establish a proper connection with the SD card. However, we are sure these instructions work, because we’ve tested them.
In this guide we’ve shown you how to use the 1.8 TFT display with the Arduino: display text, draw shapes and display images. You can easily add a nice visual interface to your projects using this display.