Today it is almost impossible to find a person who would still use a CRT monitor or an old CRT TV. This technique was quickly and successfully superseded by LCD models based on liquid crystals. But matrices are no less important. What are liquid crystals and matrices? You will learn all this from our article.
Backstory
For the first time the world learned about liquid crystals in 1888, when the famous botanist Friedrich Reinitzer discovered the existence of strange substances in plants. He was amazed that some substances, which initially have a crystalline structure, completely change their properties when heated.
So, at a temperature of 178 degrees Celsius, the substance first became cloudy, and then completely turned into a liquid. But the discoveries didn't end there. It turned out that the strange liquid electromagnetically manifests itself as a crystal. It was then that the term "liquid crystal" appeared.
How LCD matrices work
This is what the matrix is based on. What is a matrix? itambiguous term. One of its meanings is a laptop display, LCD monitor or modern TV screen. Now we will find out what the principle of their work is based on.
And it is based on the usual polarization of light. If you remember the school physics course, then it just tells that some substances are capable of transmitting light of only one spectrum. That is why two polarizers at an angle of 90 degrees may not transmit light at all. In the case when there is some device between them that can turn the light, we will be able to adjust the brightness of the glow and other parameters. In general, this is the simplest matrix.
Simplified matrix arrangement
A normal LCD display will always consist of several permanent parts:
- Illumination lamps.
- Reflectors that ensure the uniformity of the above illumination.
- Polarizers.
- Glass substrate with conductive contacts.
- Some amount of the notorious liquid crystals.
- Another polarizer and substrate.
Each pixel of such a matrix is formed from red, green and blue dots, the combination of which allows you to get any of the available colors. If you turn them all on at the same time, the result is white. By the way, what is the resolution of the matrix? This is the number of pixels on it (1280x1024, for example).
What are matrices?
To put it simply, they are passive (simple) and active. Passive - the simplest, in thempixels fire sequentially, line by line. Accordingly, when trying to establish the production of displays with a large diagonal, it turned out that it was necessary to disproportionately increase the length of the conductors. As a result, not only did the cost increase significantly, but the voltage also increased, which led to a sharp increase in the number of interference. Therefore, passive matrices can only be used in the production of inexpensive monitors with a small diagonal.
Active varieties of monitors, TFT, allow you to control each (!) Of the millions of pixels separately. The fact is that each pixel is controlled by a separate transistor. To prevent the cell from losing charge prematurely, a separate capacitor is added to it. Of course, due to such a scheme, it was possible to significantly reduce the response time of each pixel.
Mathematical justification
In mathematics, a matrix is an object written as a table, the elements of which are at the intersection of its rows and columns. It should be noted that matrices are generally widely used in computers. The same display can be interpreted as a matrix. Since each pixel has certain coordinates. Thus, any image that is formed on the laptop display is a matrix, the cells of which contain the colors of each pixel.
Each value takes up exactly 1 byte of memory. A little? Alas, even in this case, only one FullHD frame (1920 × 1080) will take a couple of MB. How much space do you need for a 90 minute movie? That's whythe image is compressed. In this case, the determinant is of great importance.
By the way, what is the matrix determinant? It is a polynomial that combines the elements of a square matrix in such a way that its value is preserved through transposition and linear combinations of rows or columns. In this case, a matrix is understood as a mathematical expression that describes the arrangement of pixels in which their colors are encoded. It is called square because the number of rows and columns in it is the same.
Why is this so important? The fact is that the Haar transform is used in coding. Essentially, the Haar transform is the rotation of points in such a way that they can be conveniently and compactly encoded. As a result, an orthogonal matrix is obtained, for the decoding of which the determinant is used.
Now we will look at the main types of the matrix (we have already found out what the matrix itself is).
TN+film
One of the cheapest and most common display models today. It has a relatively fast response time, but rather poor color reproduction. The problem is that the crystals in this matrix are located so that the viewing angles are negligible. To combat this phenomenon, a special film has been developed that allows for slightly wider viewing angles.
The crystals in this matrix are arranged in a column, thus resembling soldiers on parade. The crystals are twisted into a spiral, thanks to which they cling perfectly tightly to each other. In order for the layers to adhere well to the substrates, specialnotches.
An electrode is connected to each crystal, which regulates the voltage on it. If there is no voltage, then the crystals rotate 90 degrees, as a result of which light passes freely through them. It turns out the usual white pixel of the matrix. What is red or green? How does it work?
As soon as the voltage is applied, the spiral is compressed, and the degree of compression directly depends on the strength of the current. If the value is maximum, then the crystals generally cease to transmit light, resulting in a black background. To get the gray color and its shades, the position of the crystals in the spiral is adjusted so that they let in some light.
By the way, by default, all colors are always activated in these matrices, resulting in a white pixel. That is why it is so easy to identify a burnt pixel, which always appears as a bright dot on the monitor. Given that matrices of this type always have problems with color reproduction, it is very difficult to achieve black display as well.
To somehow remedy the situation, the engineers placed the crystals at an angle of 210°, resulting in improved color quality and response time. But even in this case, there were some overlaps: unlike the classic TN-matrices, there was a problem with shades of white, the colors turned out to be washed out. This is how DSTN technology was born. Its essence is that the display is divided into two halves, each of which is controlled separately. The display quality has improved dramatically, butincreased the weight and cost of monitors.
This is what a matrix is in a TN+film type laptop.
S-IPS
Hitachi, having suffered enough from the shortcomings of the previous technology, decided not to try to improve it anymore, but simply invent something radically new. Moreover, in 1971 Günter Baur found out that crystals can be placed not in the form of twisted columns, but laid parallel to each other on a glass substrate. Of course, in this case, the transmitting electrodes are also attached there.
If there is no voltage on the first polarizing filter, light passes freely through it, but is retained on the second substrate, the plane of polarization of which is always at an angle of 90 degrees with respect to the first. Due to this, not only does the response speed of the monitor increase dramatically, but the black color is really black, and not a variation of a dark gray tint. In addition, the extended viewing angles are a big advantage.
Flaws of technology
Alas, but the rotation of the crystals, which are parallel to each other, takes much more time. That is why the response time on older models reached a truly cyclopean value, 35-25 ms! Sometimes it was even possible to observe a loop from the cursor, and it was better for users to forget about dynamic scenes in toys and films.
Because the electrodes are on the same substrate, much more power is required to turn the crystals in the desired direction. And therefore everythingIPS monitors rarely earn an Energy Star for economy. Of course, to illuminate the substrate also requires the use of more powerful lamps, and this does not improve the situation with increased power consumption.
The manufacturability of such matrices is high, and therefore, until recently, they were very, very expensive. In short, with all the advantages and disadvantages, these monitors are great for designers: their color quality is excellent, and response time can be sacrificed in some cases.
This is what an IPS panel is.
MVA/PVA
Since both of the above types of sensors have flaws that are virtually impossible to eliminate, Fujitsu has developed a new technology. In fact, MVA / PVA is a modified version of IPS. The main difference is the electrodes. They are located on the second substrate in the form of peculiar triangles. This solution allows crystals to respond faster to voltage changes, and color rendering becomes much better.
Camera
And what is a matrix in a camera? In this case, this is the name of the conductor crystal, which is also known as a charge-coupled device (CCD). The more cells in the camera matrix, the better it is. When the camera shutter opens, a stream of electrons passes through the matrix: the more there are, the stronger the current that occurs. Accordingly, no current is formed in the dark parts. Areas of the matrix that are sensitive to certain colors, inresult and form a complete image.
By the way, what is the size of the matrix, if we talk about computers or laptops? It's simple - this is the name of the screen diagonal.
