1' definition
Power terminals and display elements of instruments and meters are liquid crystal modules, which are equivalent to picture tubes in CRT.
Other parts include power supply circuit, signal processing circuit and, of course, shell and so on.
The module is mainly divided into screen and backlight module. These two components are assembled together, but work independently of each other (that is, the circuits are not related).
The principle of liquid crystal display is that the backlight module emits uniform surface light, and the light is transmitted to our eyes through the LCD screen. The function of the screen is to process the light pixel by pixel to display the image. Both parts contain a lot of parts, so I won't go into details here.
Fold and edit the production process of this section.
microminiature/subminiature tube
Surface mounting technology
That is, surface mount technology, which is a more traditional installation method. Its advantage is high reliability, but its disadvantage is large volume and high cost, which limits the miniaturization of LCM.
A rectangular loaf of bread
chip on board
That is to say, the chip is bonded on the PCB, because the control of IC manufacturers is related to LCD.
The production of chips is reducing the output of QFP (a kind of QFP(SMT) package), so the traditional SMT method will be gradually replaced in future products.
label
Automatic adhesive tape bonding
Anisotropic conductive adhesive connection mode. The encapsulation form is TCP (carrier tape).
The packaged IC is fixed on LCD and PCB with anisotropic conductive adhesive. This installation method can reduce the weight and volume of LCM, and the installation is convenient and reliable!
Embedded chip on glass
The chip is directly bonded to the glass. This installation method can greatly reduce the volume of the whole LCD module and is easy for mass production. It is suitable for LCD used in consumer electronic products, such as mobile phones, PDA and other portable electronic products. Driven by IC manufacturers, this installation mode will be the main connection mode between IC and LCD in the future.
COF
Chip on film
The chip is directly mounted on the flexible PCB. This connection mode is highly integrated, and peripheral components can be installed on flexible PCB together with IC. This is a new technology and has entered the trial production stage.
Fold and edit the main parameters of this paragraph.
Folding contrast
Accessories such as control IC, optical filter and orientation film used in LCD panel manufacturing are related to the contrast of the panel. For ordinary users, the contrast ratio of 350: 1 is enough, but this contrast level can not meet the needs of users in professional fields. Compared with CRT display, it can easily achieve a contrast ratio of 500: 1 or even higher. Only high-end liquid crystal displays can reach this level. Because the contrast is difficult to measure accurately with instruments, you should look at it yourself when choosing.
Tip: Contrast is very important. It can be said that the choice of LCD is more important than the bright spot. When you know that customers buy LCDs for entertainment and watching DVDs, you can emphasize that contrast is more important than no bad spots. When we watch streaming media, the brightness of the source is generally not large, but to see the contrast of the character scene and the texture change from gray to black, it depends on the contrast. Excellent VG and VX always emphasize the index of contrast. VG9 10S is the contrast ratio of 1000: 1 At that time, we compared this with one of Samsung and a dual-head graphics card. Samsung LCD is obviously inferior. You can try it if you are interested. In the 256-level gray scale test in the test software, you can see more small gray squares when you look up, which shows that the contrast is very good!
Folding brightness
Liquid crystal is a kind of substance between solid and liquid, which cannot emit light by itself and needs an additional light source. Therefore, the number of lamps is related to the brightness of LCD. The earliest LCD only had two lights. Up to now, the lowest-end Volkswagen LCD is four lights, and the high-end LCD is six lights. The design of the four lamps can be divided into three arrangements: one is that there is one lamp on each side, but there is a shadow in the middle. The solution is that four lights are arranged horizontally up and down, and the last one is in the form of "U", which is actually two lights in disguise. In fact, the six-lamp design is to use Three Lamps District. The manufacturer bends Three Lamps District into a "U" shape, and then places it in parallel to achieve the effect of six lamps.
Tip: Brightness is also an important indicator. The brighter the liquid crystal, the brighter it will stand out from a row of liquid crystal walls. The highlight technologies we often see in CRT (Youpai is called highlight, Philips is called bright, and BenQ is called sharp color) are all produced by increasing the current of cathode tube and bombarding phosphor. This technology is generally adopted at the expense of image quality and display life. When you watch a DVD at 5X brightness, it's all burnt up at a glance. If you want to read the text, you have to honestly return to the ordinary text mode. This design is actually to make people not highlight frequently. The principle of LCD display brightness is different from CRT, which is realized by the brightness of backlight behind the panel. Therefore, it is necessary to design more lamps to make the light uniform. When I sold LCDs in the early days, I told others that it was awesome to have three LCDs, but at that time Chi Mei CRV began to do it. This six-lamp design, coupled with the strong light of the lamp itself, makes the panel bright. This masterpiece is represented by VA7 12 in Youpai. But all highlighted panels will be fatal and the screen will leak light. This term is rarely mentioned by ordinary people. Personally, I think it is very important. Light leakage indicates that the LCD is not black, but gray. So a good LCD should not emphasize brightness blindly, but should emphasize contrast more. Excellent VP and VG series are products that don't talk about brightness but only contrast!
Folding signal response time
Response time refers to the response speed of liquid crystal display to input signals, that is, the response time of liquid crystal from dark to bright or from bright to dark, usually in milliseconds (ms). To make this clear, we should also talk about the human eye's perception of dynamic images. There is a phenomenon of "visual residue" in the human eye, and the high-speed moving picture will form a short impression in the human brain. Cartoons, movies, etc. So far, the latest game only applies the principle of visual residual, so that a series of gradual images are displayed in front of people quickly and continuously, and then dynamic images are formed. Generally speaking, the acceptable display speed of pictures is 24 frames per second, which is also the origin of the 24-frame playback speed of movies. If the display speed is lower than this standard, people will obviously feel the pause and discomfort of the picture. According to this index, the display time of each picture needs to be less than 40ms, so for LCD, the response time of 40ms becomes a hurdle, and the display below 40 ms will appear obvious "tailing" or "afterimage" phenomenon, which makes people feel very chaotic. If you want to make the image smooth, you need to reach the speed of 60 frames per second.
I use a very simple male.
The number of frames per second under the corresponding reaction time is calculated as follows:
Response time 30ms= 1/0.030= approximately 33 frames per second are displayed.
The response time is 25ms= 1/0.025= about 40 frames are displayed every second.
Response time16 ms =1/0.016 = approximately 63 frames are displayed every second.
Response time12 ms =1/0.012 = about 83 frames are displayed per second.
Response time 8ms= 1/0.008= approximately 125 frames are displayed every second.
Response time 4ms= 1/0.004= about 250 frames per second are displayed.
Response time 3ms= 1/0.003= about 333 frames per second are displayed.
Response time 2ms= 1/0.002= about 500 frames per second are displayed.
Response time 1 ms = 1/0.00 1= approximately 1000 frames are displayed every second.
Tip: From the above, we know the relationship between response time and frame number. It seems the shorter the response time, the better. At that time, the LCD market had just started, and the minimum acceptable range of response time was 35ms, mainly products represented by EIZO. Later, BenQ's FP series introduced 25 ms, which was almost imperceptible from 33 frames to 40 frames. The real qualitative change is 16MS, which displays 63 frames per second, meeting the requirements of movies and general games, so up to now, 16MS is not out of date. With the improvement of panel technology, BenQ and Youpai started a speed struggle. Youpai was released to 1MS from 8MS, 4ms and 4ms, so it can be said that 1MS is the final argument of liquid crystal speed. For game enthusiasts, the speed of 1MS means that CS can shoot more accurately, at least psychologically, so customers will recommend VX series monitors. But when selling, people should pay attention to the text difference between gray-scale response and full-color response. Sometimes grayscale 8MS and full-color 5MS mean the same thing, just like when we used to sell CRT, we said that the dot pitch was .28,28, and LG had to say .2655. The horizontal point distance is ignored. In fact, both sides said the same thing. Now recently LG has come up with the sharpness of 1600: 1, which is also a concept hype. Basically, most users have very few screens. Only LG can do 1600: 1, and everyone stays at 450. When it comes to consumers, it clearly means sharpness and contrast, just like AMD's PR value, which is meaningless.
Folding perspective
The viewing angle of liquid crystal is a headache. When the backlight passes through the polarizer, the liquid crystal and the alignment layer, the output light will be directional. In other words, most of the light is emitted vertically from the screen, so when you look at the LCD from a larger angle, you can't see the original color, or even see all white or all black. In order to solve this problem, manufacturers also began to develop wide-angle technology. So far, there are three popular technologies: TN+ thin film, IPS (in-plane exchange) and MVA (multi-domain vertical arrangement).
TN+ membrane technology is to add a wide viewing angle compensation film on the original basis. This compensation film can increase the viewing angle to about 150 degrees, which is a simple and easy method and widely used in liquid crystal displays. But this technology can't improve the performance such as contrast and response time. Perhaps TN+ film is not the best solution for manufacturers, but it is the cheapest solution, so most manufacturers in Taiwan Province Province use this method to build 15 inch LCD.
IPS(IN-PLANE -SWITCHING) technology claims that it can make the visual angle of up, down, left and right reach 170 degrees. Although IPS technology increases the viewing angle, using two electrodes to drive liquid crystal molecules requires more power consumption, which will increase the power consumption of liquid crystal displays. In addition, it is fatal that the response time of driving liquid crystal molecules will be very slow.
MVA (multi-domain vertical alignment) technology, the principle is to add protrusions to form multiple visual areas. Liquid crystal molecules are not completely vertically aligned at rest, but horizontally aligned after voltage is applied, so that light can pass through each layer. MVA technology improves the viewing angle to more than 160 degrees, and provides shorter response time than IPS and TN+ films. This technology was developed by Fujitsu. At present, Chi Mei in Taiwan Province Province (Chi Li is a subsidiary of Chi Mei in Chinese mainland) and AUO in Taiwan Province Province are authorized to use this technology. VX2025WM is the representative work of this kind of panel. Horizontal vertical viewing angle 175 degrees, basically no visual dead angle, no bright spot promised. Perspective can be divided into parallel perspective and vertical perspective. The horizontal angle is centered on the vertical central axis of the liquid crystal, and the angular range of the image can be clearly seen by moving left and right. The vertical angle is centered on the parallel central axis of the display screen, and the angle range of the image can be clearly seen by moving up and down. The viewing angle is in degrees. At present, the commonly used labeling form is to directly label the total horizontal and vertical range, such as 150/ 120 degrees. At present, the lowest viewing angle is 120/ 100 degrees (horizontal/vertical). Below this value is unacceptable, and it is better to reach 100 degrees.
Fold and edit the classification of LCD modules in this paragraph.
Folding digital display liquid crystal module
This is a functional component assembled by segment LCD and ASIC, which can only display numbers and some identification symbols. Segmented LCD devices are mainly used for portable and pocket devices. Because of the small size of these devices, try not to design the display part as a separate component. Even if some application fields need separate display components, they should have the functions of receiving, processing, storing and transmitting information in addition to the display function. They are very popular in the market because they have some general and specific functions. Common digital LCD modules are as follows.
(1). Counting module
This is a counting display component assembled by seven-segment liquid crystal display devices with different digits, decoding drivers or counters. It has the functions of recording, processing and displaying numbers. At present, the main products that can be seen in the domestic digital LCD module market are CD4055 decoding-driven unit LCD modules, as well as ICM72ll, ICM723 1, ICM7232, CDl4543, UPDl4500 1, 4-bit, 6-bit, 8-bit, 10,/.
Clear function: Although they are all called "counting modules", most of them cannot be counted directly. Some of their input ports are only BCD code interfaces, some are BCD code plus gated input interfaces, and some are interface forms that can be directly connected with serial ports and parallel ports. If you need to calculate or record a string of numbers, you must also configure the corresponding circuit. Of course, there are also products matching the counting circuit on the module.
Identification structure: LCD devices have different installation methods and structures. Therefore, attention should be paid to its structural characteristics when selecting. Generally speaking, this counting module is composed of zebra conductive rubber strip, plastic (or metal) press frame and PCB board, which is used to assemble liquid crystal display devices and integrated circuits. There are several types of external leads, such as solder joints, pins and circuit board pins.
Pay attention to power supply: try to use a unified power supply for a device. Common LCD device counting modules include single power supply and dual power supply, with different specifications such as 5V and 9V.
(2). Measuring module
This is a module composed of multi-segment liquid crystal display devices and integrated circuit chips with decoding, driving, counting and A/D conversion functions. Because the integrated circuit used has the function of A/D conversion, the input analog electric signal can be converted into digital quantity and displayed. We know that any physical quantity, even chemical quantity (such as pH, etc. ) can be converted into analog electricity, so this module can monitor and display any value as long as it is equipped with a sensor, which is very convenient to use. The integrated circuit models used in the metering module mainly include ICL7 106, ICL716, ICL7 126, ICL7 136, ICL7 135 and ICL7/KL. The functions of these integrated circuits. As a measurement product, it must be measured and identified according to the regulations. Approved by the metrological department, the product is affixed with a metrological certificate.
(3). Timing module
The timing module uses the liquid crystal display device for the longest time, and assembling the liquid crystal display device with the timing integrated circuit is a fully functional timer. Because it has no shell of finished watch, it is called timing module. Although the timing module is widely used, it is difficult to buy a universal and standard timing module in the market. You can only buy or order the right watch core from the electronic watch manufacturer. Although the timing module and the counting module are similar in appearance, their display modes are different. The number displayed by the timing module consists of two numbers in groups, and each number of the counting module is arranged continuously. Because many timing modules also have timing and control functions, such modules can be widely assembled on some electrical equipment, such as tape recorders, CD players, microwave ovens, rice cookers and other electrical appliances.
Folding LCD dot matrix character module
The liquid crystal module of character liquid crystal symbol is composed of dot matrix character liquid crystal display device, special row and column driver, controller, necessary connectors and structural parts, and can display numbers and western characters. This dot matrix character module itself has a character generator with large display capacity and rich functions. Generally, this module can also display at least 8 characters, 1 line or 16 lines or more. The lattice arrangement of this module consists of a group of 5×7, 5×8 or 5× 1 1 pixels. Each group is 1 bit, there is a little space between each bit, and there is a space between rows, so the graph cannot be displayed.
Generally, in module control and driving, there are solidified font CGROM with 192 font and random access memory CGRAM which allows users to customize and establish special characters, and allows users to establish 8 characters in a 5×8 lattice.
Folding lattice graphic liquid crystal module
Dot matrix graphic liquid crystal module This module is also a kind of dot matrix module, which is characterized by the continuous arrangement of dot matrix pixels without gaps between rows and columns. Therefore, continuous and complete graphics can be displayed. Because it is also composed of X-Y matrix pixels, it can display both characters and graphics.
(1). Row and column drive.
This is a module that must be externally connected with a dedicated controller. Its module is only equipped with general row and column drivers, and actually only has the general driving output of pixels, while the input generally only has data input, shift signal input, latch input and AC signal input. , such as HD44 100, IID66 100, etc. Although the module needs an adaptive controller, it also leaves users the freedom to choose different controllers.
(2). Row-and-column drive control type
This is a module that can directly interface with the computer, and the computer directly controls the driver. The column driver used in this kind of module has I/O bus data interface, which can directly hang the module on the bus of the computer, eliminating the special controller, so it is beneficial to reduce the cost of the whole system. It is very suitable for users who are familiar with computer software programming with few pixels and few functions. But it will take up some resources of your system.
(3). Row and column control type
This is a matrix graphics module with built-in controller. It is also a popular type. The module is not only equipped with the first class equal rank driver, but also equipped with special controllers such as T6963C. The controller is the interface between the LCD driver and the computer. It is controlled by the computer in the simplest way, receives and feeds back all kinds of information from the computer, manages the display buffer through its own independent information processing, provides various signals and pulses to the driver, and controls the driver to realize the display function of the module. This controller has its own set of special instructions and its own character generator CGROM. Users must be familiar with the detailed description of this controller before they can summarize it. This module frees users from a series of work such as designing, processing and making controllers, which makes computers avoid the complicated control of the display and saves the internal resources of the host system. If you need technology, please consult: www.rxflcd.coM.
Module picture reference