01Overview of Screen Technology
◆ Basic structure of capacitive touch screen
In the evolution of touch screen technology, we have witnessed the competitive landscape from IPS, AMOLED, SLCD to OGS, while also witnessing the rise of In cell and n-cell technologies. In order to gain a deeper understanding of the three screen technologies of In Cell, On Cell, and OGS, we first need to analyze the basic structure of the screen. The structure of a capacitive touch screen is divided into three layers: the top layer is a glass cover plate, which is responsible for protecting the screen and transmitting tactile sensations; The middle layer is a capacitive touch layer, responsible for sensing and responding to touch signals; The bottom layer is the display panel, responsible for presenting images and colors.
The capacitive touch layer is composed of an ITO touch film layer and an ITO substrate. The display panel consists of an upper substrate, a liquid crystal layer, and a lower substrate from top to bottom. In the early days, frame pasting technology created a layer of air between the touch layer and the display panel, which affected the display effect. However, by using full lamination technology to eliminate this layer of air, the reflection problem of the screen has been significantly improved, making it more transparent when lit up and darker when turned off, eliminating the gray and white appearance.
Differences in Traditional Screen Structure
Traditional G/G and GFF screens both follow a similar structure: cover glass, touch layer, and display panel. But the difference in touch layer is the key to these two screens. Specifically, the structure of G/G and GFF screens is similar, with the main difference being the touch layer. The touch layer of G/G screens consists of one layer of ITO substrate and one layer of ITO touch film, while the touch layer of GFF screens consists of two layers of ITO substrate and two layers of ITO touch film (named ITO: X and ITO: Y respectively). Obviously, G/G screens have an advantage in thickness.

Comparison of Emerging Screen Technologies
Nowadays, OGS screens are favored by touch panel manufacturers, while In Cell and On Cell screens are highly regarded by display panel manufacturers such as Apple LG、 Samsung and Sharp, among others. Both of these screen structures have abandoned the traditional touch glass layer, thus achieving a thinner and lighter design. However, the key difference between the two lies in the integration position of the touch layer. Specifically, the OGS screen uses the same glass to achieve touch functionality; In Cell embeds the touch film layer into the display panel; On Cell places the touch film layer on top of the upper substrate. This difference affects screen design and performance.

02Comparison of In Cell, On Cell, and OGS
◆ Display effect differences
OGS screens perform better than In Cell and On Cell in terms of transparency and visual effects. Therefore, although well-known brands such as Apple and Samsung use In Cell screens, their simple screen transparency and visual effects are not superior to some domestic phones that use OGS screens.
◆ Lightweight and impact resistant
In terms of lightness and thinness, In Cell stands out with its lightweight and compact features. In Cell is the lightest and thinnest due to the integration of the touch layer into the display panel, which is also one of the reasons why iPhone can maintain its lightness and thinness even with a metal body. In contrast, OGS and On Cell are slightly inferior in terms of thinness. In terms of screen impact and drop resistance, On Cell performs the best, followed by OGS, while In Cell is relatively weaker. It is worth noting that OGS, by combining the cover glass with the touch layer, may weaken the strength of the glass during the processing, making the screen relatively fragile.

◆ Touch effect and technical complexity
OGS screens have higher sensitivity, while In Cell and On Cell interaction have lower sensitivity, but rely less on touch chips. High sensitivity may also bring problems, such as "screen jumping" phenomenon, which may be caused by fine dust, sweat or water vapor leading to misoperation of the touch screen. In contrast, in Cell screens directly integrate touch and liquid crystal layers, resulting in higher sensing noise and requiring specialized touch chips for filtering and correction. OGS and On Cell screens have relatively low dependence on touch chips.

Production cost and yield rate
From a technical perspective, the technical complexity of In Cell and On Cell is higher than OGS, and the difficulty of production control also increases accordingly, leading to an increase in manufacturing costs. In terms of yield, the initial production yield of In Cell screens was relatively low, which affected the supply of iPhone 5. But with the continuous technological investment and process improvement of manufacturers, In Cell technology was once affected by low yield rates, and now the yield rate has increased, approaching On Cell and OGS.

**1. OLED screen**



OLED screen, also known as organic light-emitting diode screen, is a self luminous screen that does not require a backlight source. OLED screens have advantages such as self illumination, high contrast, and vivid colors, and can also be made very thin, making them very popular in mobile phone design. However, OLED screens also have some drawbacks, such as relatively short lifespan and susceptibility to screen burn-in.

The working principle of OLED screens is to utilize the characteristic of organic materials emitting light under the action of current. When current passes through organic materials, the materials emit light, thereby achieving image display. Each pixel of an OLED screen emits light independently, allowing for high contrast and high saturation color display. Meanwhile, OLED screens also have the advantages of fast response speed and low power consumption, making them very suitable for displaying dynamic images and videos.

The advantages of OLED screens also include:

-Thin and light: OLED screens do not require a backlight and can be made very thin, making them very suitable for portable devices such as smartphones.

-High contrast: OLED screens have a very high contrast ratio, reaching 100000:1 or more, allowing them to display very deep black and bright colors.

-Wide viewing angle: OLED screens have a very wide viewing angle, reaching over 180 degrees, so the color and contrast of the image will not change when viewed from different angles.

The drawbacks of OLED screens include:

-Relatively short lifespan: The organic materials of OLED screens have a relatively short lifespan and are prone to screen burn-in, which means that when the same image is displayed for a long time, traces will be left on the screen.

-High cost: The production cost of OLED screens is relatively high, so the price is also relatively expensive.

-Insufficient brightness: OLED screens have relatively low brightness, which may make it difficult to see the screen content clearly in sunlight.



**2. LCD screen**



LCD screen, also known as liquid crystal display screen, is a type of screen that requires a backlight source. LCD screens have the advantages of low cost, high brightness, long lifespan, and also have good performance in color reproduction and contrast. However, LCD screens also have some drawbacks, such as relatively slow response speed and smaller viewing angles.

The working principle of LCD screens is to control the transmittance of light by utilizing the orientation changes of liquid crystal molecules under the action of an electric field. When an electric field acts on liquid crystal molecules, they undergo orientation changes, thereby altering the transmittance of light and achieving image display. The backlight source of LCD screens usually uses LED or CCFL (cold cathode fluorescent lamp), which can provide uniform brightness distribution.

The advantages of LCD screens include:

-Low cost: The production cost of LCD screens is relatively low, so the price is also relatively cheap.

-High brightness: LCD screens have relatively high brightness, and the screen content can be seen clearly in sunlight.

-Long lifespan: LCD screens have a relatively long lifespan and are less prone to screen burn-in.

The disadvantages of LCD screens include:

-Relatively slow response speed: LCD screens have a relatively slow response speed and may experience ghosting when displaying dynamic images.

-Small viewing angle: LCD screens have a relatively small viewing angle, and when viewed from different angles, the color and contrast of the image will change.

-Relatively low contrast: LCD screens have relatively low contrast and cannot display very deep black and bright colors.



**3. AMOLED screen**



AMOLED screen, also known as active matrix organic light-emitting diode screen, is a self luminous screen similar to OLED screen. AMOLED screens have the advantages of fast response speed, high contrast, vivid colors, and can also be made very thin, making them very popular in mobile phone design. However, AMOLED screens also have some drawbacks, such as relatively short lifespan and susceptibility to screen burn-in.

The working principle of AMOLED screens is to utilize the characteristic of organic materials emitting light under the action of current. When current passes through organic materials, the materials emit light, thereby achieving image display. Each pixel of an AMOLED screen emits light independently, allowing for high contrast and high saturation color display. Meanwhile, AMOLED screens also have the advantages of fast response speed and low power consumption, making them very suitable for displaying dynamic images and videos.

The advantages of AMOLED screens include:

-Fast response speed: AMOLED screens have a very fast response speed, reaching microsecond level, making them very smooth when displaying dynamic images.

-High contrast: AMOLED screens have a very high contrast ratio, reaching 100000:1 or more, allowing them to display very deep black and vibrant colors.

-Wide viewing angle: AMOLED screens have a very wide viewing angle, reaching over 180 degrees, so the color and contrast of the image will not change when viewed from different angles.

-Thin and light: AMOLED screens can be made very thin, making them very suitable for portable devices such as smartphones.

The drawbacks of AMOLED screens include:

-Relatively short lifespan: The organic materials of AMOLED screens have a relatively short lifespan and are prone to screen burn-in, which means that when the same image is displayed for a long time, traces will be left on the screen.

-High cost: The production cost of AMOLED screens is relatively high, so the price is also relatively expensive.

-Insufficient brightness: The brightness of AMOLED screens is relatively low, and it may be difficult to see the screen content clearly in sunlight.



**4. TFT screen**



TFT screen, also known as thin-film transistor screen, is a type of screen that requires a backlight source. TFT screens have the advantages of fast response speed, high brightness, high contrast, and also have good performance in terms of viewing angle. However, TFT screens also have some drawbacks, such as inaccurate color reproduction and smaller viewing angles.

The working principle of TFT screen is to use thin film transistors (TFT) to control the brightness of each pixel. TFT is a semiconductor device that can control the brightness of pixels by changing the current. When current passes through TFT, TFT controls the brightness of pixels, thereby achieving image display. The backlight source of TFT screens usually uses LED or CCFL (cold cathode fluorescent lamp), which can provide uniform brightness distribution.

The advantages of TFT screens include:

-Fast response speed: TFT screens have a very fast response speed, reaching the millisecond level, making them very smooth when displaying dynamic images.

-High brightness: The TFT screen has relatively high brightness, and the screen content can also be seen clearly in sunlight.

-High contrast: TFT screens have relatively high contrast and can display very deep black and bright colors.

-Wide viewing angle: TFT screens have a relatively wide viewing angle, reaching over 160 degrees, so the color and contrast of the image will not change when viewed from different angles.

The disadvantages of TFT screens include:

-Color reproduction is not accurate enough: The color reproduction of TFT screens is not accurate enough, which may result in color cast.

-High power consumption: TFT screens have relatively high power consumption, which can affect the battery life of the phone.

-High cost: The production cost of TFT screens is relatively high, so the price is also relatively expensive.

Comparison of Three Packaging Technologies


1. COG (Chip On Glass): This is one of the most traditional packaging methods, with low technical barriers and low costs, and is the most commonly used technology for screens. From the English version, it can also be seen that this packaging method involves placing IC chips and FPC cables on the back glass of the screen. However, due to the IC chip being located directly below the LCD, a considerable amount of screen space is squeezed, inevitably resulting in a "chin".




2. COF (Chip On Film): Essentially, it is an upgraded version of COG and a key factor in the current screen transformation. The main principle is to place the display driver IC chip into a flexible FPC cable, and then fold it under the screen using the characteristics of the FPC itself. Specifically, through hot pressing, the Gold Bump of the IC chip and the Inner Lead on the flexible substrate circuit will be bonded together. Due to the release of space occupied by IC chips, the lower frame width can generally be reduced by at least 1.5 millimeters.






3. COP (Chip On Pi): It belongs to the process with the most reduced borders, but it should be emphasized that the premise of this process is the application of flexible OLED screens, which utilize the bending characteristics of flexible OLEDs to bend all cables and ICs below the screen. Of course, OLED is also divided into two types: hard screens and flexible screens. To use this technology, a combination of COP packaging technology and flexible OLED must be used. However, this technology still has the disadvantages of high cost and low yield rate.





After introducing the technical foundations of COG, COF, and COP, let's take a look at the practical application of COP technology on Samsung S8. This phone adopts innovative COP screen packaging technology, which allows the screen edges to bend without physical limitations, achieving a nearly borderless visual effect. This technology not only enhances the aesthetic appearance of mobile phones, but also brings them a wider display space.

1、 What is OLED flexible straight screen?



To understand the difference between the two, one must first clarify what OLED is. Simply put, OLED uses a very thin organic material coating, which can achieve self illumination without the need for backlighting. It can be understood as OLED being composed of countless "small light bulbs". But whether it's a flexible screen or a hard screen, the materials used are the same. The main difference between them is the substrate material, which is the material supporting the OLED.



Flexible screens generally use PI and other flexible materials as substrate materials

Hard screens generally use hard materials such as glass as substrate materials



What exactly is a flexible straight screen? To put it bluntly, it's just about installing OLED flexible screens into straight screen phones.





2、 What are the benefits of using a flexible straight screen?



1. Due to the use of flexible materials as substrates, flexible screens have thinner screen thickness and lighter weight, which reduces the overall thickness, size, and weight of the phone. The thickness of mobile phones with large batteries/ultra fast charging like the K50 series is extremely terrifying, and using a hard screen will make the feel even more uncomfortable.



2. Due to its softness, flexible screens will have greater improvements in screen packaging technology. The use of COP packaging technology can make the black edge of the phone chin smaller, resulting in a better phone experience.



3. Flexible screens have a soft constitution, which can better protect the screen in the event of a phone falling or bending. In the event of damage to the external screen, a flexible screen can provide greater protection from the impact.

On Samsung OLED screens, rainbow patterns may appear on hard screens. However, many netizens have found that Samsung's flexible screen does not have this problem. This can also be considered a special place.





3、 Why didn't straight screen phones use flexible screens in the beginning?



To put it simply, it's still a matter of cost. In the past few years, the cost price of flexible screens was several times higher than that of hard screens, and COP packaging technology is also a high cost and low yield technology. In this way, the cost price will rise sharply.

Summary: The difference between mobile OLED flexible screens and hard screens lies in the substrate material used for the screen. And the flexible straight screen is actually to put the flexible screen into a straight screen phone for use. Flexible screens have thinner thickness, lighter weight, and better drop resistance. When choosing a mobile phone, it is better to choose a flexible screen.

Price reference for mobile phone screensUpon entering a mobile phone repair shop, you will discover that the prices for screen replacements vary widely across different brands and models. Taking Apple phones as an example, here is a simple price reference for you:iPhone 13 seriesPrice of the outer screen: approximately 500~700 yuanPrice of the inner screen: approximately between 600 and 1300 yuanScreen assembly price: approximately around 1600~1900 yuaniPhone 14 seriesPrice of outer screen: approximately 700~900 yuanPrice of the inner screen: approximately 900~1700 yuanScreen assembly price: approximately around 1700~2300 yuaniPhone 15 seriesPrice of the outer screen: approximately around 1100 yuanPrice of the inner screen: approximately between 1200 and 2200 yuanScreen assembly price: approximately around 1700~2400 yuaniPhone 16 seriesScreen assembly price: approximately around 1700~2400 yuan
Why is it so expensive to replace a phone screen?The reason why mobile phone screens are expensive lies primarily in their complex composition. A complete mobile phone screen typically consists of an outer screen (touch screen), an inner screen (display screen), and an adhesive layer in between.When a mobile phone screen is shattered, it could be due to a cracked outer screen or simultaneous damage to both the outer and inner screens. Therefore, during the repair process, it is often necessary to replace both parts simultaneously. This not only increases the complexity of the repair but also raises the repair cost.Moreover, with the continuous development of mobile phone technology, the composition and structure of mobile phone screens are also constantly being updated and upgraded. The emergence of these new technologies may also lead to an increase in the cost of repairing mobile phone screens.In addition, apart from the cost of the phone screen itself, the technical cost of replacing a phone screen is also significant. This is because the connection between the screen and the motherboard has become increasingly precise, and even the slightest mistake can damage other components.Therefore, the cost of repairing a screen is high due to the nature of the phone screen itself and the technical difficulty of the repair process.
How to find a repair service for screen replacement of a mobile phone?There are generally three ways to repair or replace a broken mobile phone screen:Firstly, one may choose official maintenance, which is transparent in price and guaranteed in quality, but often comes at a high cost;Secondly, through third-party repair platforms, the prices are relatively cheaper.Lastly, if you have all the necessary tools, you can also try purchasing a screen and replacing it yourself.It is important to note that one must possess relevant replacement experience and knowledge reserves, otherwise it is easy to end up making a mess of the replacement process.Of course, if you want an experienced technician to replace the screen of your phone, you can always turn to Geek Repair.Whether it's a broken outer screen, damaged inner screen, or a need to replace the entire screen assembly, we offer on-site repair services. You can easily solve your phone screen issues without leaving your home.