【Updated daily①】Basic knowledge of mobile phone hardware
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Let’s start with the screen. Mobile phone screens are mainly divided into LCD and OLED types, and the author is also confused about this. In the display of ordinary TFT liquid crystals, there are components such as a backlight source, a light guide plate, a liquid crystal layer, and color filters. The backlight source emits white light; by applying different voltages to the liquid crystal layer, various degrees of obstruction can be achieved, thereby creating differences in brightness. The number of bits referred to in screens indicates how many different voltages can be applied. For example, with 8 bits, there are 2^8 possible voltage combinations, which corresponds to that many shades of gray. It’s important to note that only white light exists at this stage; it is the color filters that assign colors to the white light. TFT is the driving layer on the screen, formally known as a thin-film field-effect transistor. Each pixel is driven by a thin-film transistor integrated behind it. The panel types we mention, such as TN, VA, IPS, and CPA, are differentiated by the arrangement of liquid crystal molecules; however, their driving layers are all TFTs (that is, TFTs serve as switches in these panels, and currently TN, IPS, VA, etc. all use TFTs as switches). Almost all IPS panels on the market come equipped with TFTs. Currently, OLEDs are divided into AMOLED and PMOLED; AMOLED includes a drive layer, which is why it has TFT. What is meant here is that the colors displayed using TFT are the \"true colors\" we mentioned earlier; as for what fake colors are, the original poster doesn’t know.
The commonly mentioned IPS is an LCD technology developed by Hitachi in Japan; it is not a type of screen material but rather the name of a technology. In other words, the driving layer for IPS is actually TFT. IPS screens alter the arrangement of TFT liquid crystal molecules, granting them a wider viewing angle; pressing on the screen surface does not result in visible ripples (which is what is known as a \"hard screen\"). They also offer better color reproduction and more realistic images, advantages that ordinary TFT screens cannot match. It is worth mentioning here that when using LCD screens, people often notice bright spots on the screen that affect viewing. This is because once a transistor on the display is damaged and becomes a dead pixel, such a pixel usually appears as a bright spot; however, in IPS screens, it appears as a dark spot with no light. So there’s no need to worry about bright spots when purchasing an IPS screen (as for what dark spots look like, I’m not sure). . . ) I think LG is the best for IPS right now, seems that way. . .
Super AMOLED: The AMOLED screen consists of three layers – the AMOLED display panel, the touch sensing layer, and the outer protective glass layer. Super AMOLED lacks the middle touch sensor layer; instead, the touch sensing layer is integrated into the AMOLED display layer. Super AMOLED panels are thinner than AMOLED screens, and they are native touch panels; unlike AMOLED, which requires a touch sensor and an air layer, they offer more sensitive touch responses. Moreover, with one less layer in between, the colors displayed appear brighter. It seems to be brighter than AMOLED, with higher touch sensitivity as well. Therefore, Super AMOLED is an upgraded version of AMOLED. Super AMOLED is a proprietary product of Samsung. Super AMOLED uses oncell. On-cell is a method in which the touch panel function is integrated between the color filter substrate and the polarizing plate, while In-cell refers to a method in which the touch panel function is incorporated into the liquid crystal pixels. Oncell is simpler compared to incell technology, but currently the yield of high-quality products using incell is not high. Another thing to note is that people generally assume that a fully covered screen turns completely black when it’s in sleep mode, but this isn’t accurate; not all fully covered screens behave this way – a slight whitening can also occur. I’d appreciate it if experts could explain the reasons behind this. . . . There’s no need to mention things like OGS, right? .
Now let’s talk about high PPI and 1080P screens. When downloading the flagship models from various smartphone manufacturers, they all claim to have 1080p screens; their PPI values are around 400+ and are expected to reach 500+ by next year. But is this really necessary? The human eye cannot distinguish between screens with such high resolutions – at a certain distance, there’s no difference between 10,000 PPI and 300 PPI when viewed without glasses. In fact, a sufficient resolution is enough; too high a resolution only increases the load on the GPU and bandwidth.