TVs. Part 1. Types of TVs, lights and technology, practical differences
Hello, dear habrasoobschestvu.
I hope that this article will be able to help the same people as me - to those people who choose TV, but who do not really know the subtle technical issues in this area. I would like to share with you my thoughts and practical conclusions on the choice of a large and high-quality TV.
For the last 3 years, I watched 42 "LCD CCFL (this is when the image is formed polarized by light from fluorescent lamps passed through light filters). In 2009, there was still no 3D, and thin LED-backlit TVs only appeared and cost dishonest money. It was bought without any agony of choice for $ 1,400.
For a couple of years of contemplation, I realized that something was missing in the image. What - I could not describe, because I did not possess the necessary knowledge in this area. I knew for sure that I wanted a larger diagonal and a deeper black.
After studying the materiel, I clarified some points.
')
a) CCFL, it is also a cold cathode. Subspecies of thin fluorescent lamps located behind the matrix.
Advantages: uniform illumination.
Disadvantages: large thickness, power consumption, inability to local control of the backlight.
b) LED - light-emitting diodes. Nowadays, cold cathode TVs are almost completely supplanted.
Advantages: it is possible to make very thin TVs, low power consumption, the possibility of local control of the backlight.
A few words should be said about the local control of the backlight and the division of the LED backlight. LED lighting is divided into 2 types: edge (also known as EDGE-LED, when the LEDs are located at the edges of the matrix, their light hits the diffuser and diffused) and carpet (Full HD LED, LED Pro). Since LCD pixels themselves do not emit light, they need a backlight (as mentioned above), which is always on. Closed crystals still transmit light, so it is impossible to achieve a low black level (the lower the better) and contrast transitions in systems with edge illumination. TVs of the highest level use carpet lights (when the LEDs are located directly behind the matrix). This makes it possible to increase the uniformity of the backlight and introduce segmented illumination control, when the individual diodes responsible for the areas on the screen can dim the brightness depending on the scene on the screen. In fact, there are only 2 series of carpet lights - the 9th Philips series and the 9th Sony series. In the 9th LG series, there is also a carpet light, but its implementation is worse than the edge one in competitive solutions.
The problem is partially solved by a segmented LED light.
a) IPS (only LG currently produces). Matrixes, which, in my opinion, are ideal for low and medium level TV.
Advantages: large viewing angles.
Disadvantages: high black level (~ 0.16 nits), long response time.
They are installed on LG 3–9 series TVs (that is, virtually everything, without division into levels), Philips 4, 6 series, Panasonic of different variations and many others.
b) S-PVA (manufactured by Samsung). Matrix TV class above.
Advantages: deeper black (0.05-0.1 nit, depending on the implementation of the backlight).
Installed on Samsung TV 7-8 series, Sony 7-8 series, Philips 7-8 series and some others.
c) UV²A (manufactured by Sharp). In my opinion, the most perfect type of matrix.
Advantages: corners are larger than those of S-PVA (but smaller than those of IPS). The deepest black level (0.02 - 0.06 nits)
Disadvantages: Sharp produces them in insufficient quantities.
Installed on Philips 9-series TVs and Sharp top series.
The image is formed by the luminescence of the phosphor under the action of UV rays.
Each plasma cell is an independent light source, so the TV does not require lighting. Previously, plasma TVs had a very large thickness and cell size, so they were very cumbersome and the Full HD diagonal started from 50-60 ". Now the thickness of modern plasma TVs does not exceed 3-4 cm, and the diagonal starts from 42".
Plasma TVs do not have different types of matrixes with marketing names, but there are panel generations (the most perfect is the 15th).
Now the plasma is almost superseded by LCD-TVs and only 3 companies are engaged in its production: Panasonic, Samsung and LG (and only the first 2 have their own developments). This is due to the unprofitability of production, competition from LCD TVs and their popularization. But the plasma holds the first position in the large diagonals.
There are other types of televisions, such as projection laser televisions, but their development has already been discontinued.
LCD:
Benefits:
- relatively low cost of production, which allows manufacturers to get quite a high profit and invest in production.
- The static method of imaging (without dithering) is good for displaying images and photos.
- Great for a static image and not afraid of it.
- LCD TVs have high brightness and low power consumption
disadvantages
- High black level (from 0.02 nits in a UV²A matrix with carpet backlighting up to 0.2 nits in IPS).
- Great response time
- Lack of volume and depth of the image
- Dynamic resolution without artificial tricks 300 - 700 lines.
Plasma
Benefits
- The overall depth of the image. In general, when delivering high-quality content, the image on the plasma is noticeably different from that in the LCD: it has greater depth and color saturation, has a pronounced effect of volume.
- Low black level (0.008 nits in 2012 Panasonic models).
- Have a dynamic resolution without artificial tricks of 1080 lines.
- Excellent for dynamic images (movies), well reveal high-quality content.
- Actually there is no response time.
- Free viewing angles
disadvantages
- It is not suitable for connecting to a computer because of the residual image
- Worse show photos (as the gradations are obtained by dithering)
- Large power consumption, not all models have high brightness.
- High production cost, low margin - it is becoming more and more difficult for manufacturers to stay afloat.
OLED
The newest imaging technology in televisions. Self-emitting organic LEDs are used. Like plasma, these are self-emission displays that do not require illumination.
Now only a few serial samples are released at a price ten times higher than similar LCD and plasma TVs, but LG promises that in 3 years OLED TVs of similar LCD and plasma diagonals will cost 1.5 times more.
Benefits:
- low response time and high contrast, as in plasma, since there are no mechanically rotating molecules and constant backlighting, as in the LCD.
- profitability
- wide viewing angles.
Disadvantages:
- different pixel degradation over time (just like in plasma, which results in residual images and pixel burnout). Now they are trying to compensate for it programmatically.
- Low service time: about 10,000 hours (for example, the LCD has 60,000 hours and the plasma has 100,000 thousand hours).
Measured characteristics:
- Black level (MLL, Minimum luminescence level) - the black level that shows the TV when the signal is 0. [nit]
- Brightness - the level of brightness that shows the TV when it receives a 255 signal.
These 2 characteristics are measured together when a “chessboard” is displayed on the TV (ANSI method) - alternation of black and white areas. Calculates the brightness of each area, the arithmetic average of the brightness of black and white areas.
- Contrast. The difference between the arithmetic average of black and white areas when black areas are taken as a unit.
ANSI contrast of IPS matrices is ~ 1000: 1, S-PVA - 3500: 1, UV²A - 5000: 1, plasma - 12000: 1.
- Color accuracy (DeltaE, deviation from the standard). An input signal is applied, the output signal is measured. The greater the deviation - the less accurate color reproduction. It is believed that the naked eye is unable to notice a deviation of DeltaE <3, and zero indicates perfect color rendering.
- Viewing angles. The smaller the viewing angle of the matrix, the more distorted the color. The smallest angles are LCD S-PVA matrix. The largest - plasma panels.
- Dynamic resolution. As you know, almost all TVs have a static resolution of 1080 lines (1920x1080 pixels), but the dynamic resolution (what the TV shows when movement occurs on the screen) is often different. For this purpose, backlight flickering, frame interpolation and other tricks are introduced in LCD TVs.
Subjective characteristics
These include the volume of the image, which is formed by a combination of black level and color saturation, the “cinematicity” of the image, the effect of presence.
Thanks for attention.
If the article seems interesting, in the next part I will write about the choice of the diagonal, the 3D types, their practical difference, about the interpolation of the image and try to debunk some myths.
I hope that this article will be able to help the same people as me - to those people who choose TV, but who do not really know the subtle technical issues in this area. I would like to share with you my thoughts and practical conclusions on the choice of a large and high-quality TV.
For the last 3 years, I watched 42 "LCD CCFL (this is when the image is formed polarized by light from fluorescent lamps passed through light filters). In 2009, there was still no 3D, and thin LED-backlit TVs only appeared and cost dishonest money. It was bought without any agony of choice for $ 1,400.
For a couple of years of contemplation, I realized that something was missing in the image. What - I could not describe, because I did not possess the necessary knowledge in this area. I knew for sure that I wanted a larger diagonal and a deeper black.
After studying the materiel, I clarified some points.
')
I Type of imaging.
Today, there are 3 types of imaging on modern TVs:1 LCD.
The most common type of televisions. Images in such TVs are obtained using polarized light, several light filters and controlled liquid crystals.1.1 Types of backlight LCD-TVs.
Since the image that we see on the LCD TV screen is obtained as a result of the passage of polarized light from the backlight source, it is necessary to designate 2 types of backlight:a) CCFL, it is also a cold cathode. Subspecies of thin fluorescent lamps located behind the matrix.
Advantages: uniform illumination.
Disadvantages: large thickness, power consumption, inability to local control of the backlight.
b) LED - light-emitting diodes. Nowadays, cold cathode TVs are almost completely supplanted.
Advantages: it is possible to make very thin TVs, low power consumption, the possibility of local control of the backlight.
A few words should be said about the local control of the backlight and the division of the LED backlight. LED lighting is divided into 2 types: edge (also known as EDGE-LED, when the LEDs are located at the edges of the matrix, their light hits the diffuser and diffused) and carpet (Full HD LED, LED Pro). Since LCD pixels themselves do not emit light, they need a backlight (as mentioned above), which is always on. Closed crystals still transmit light, so it is impossible to achieve a low black level (the lower the better) and contrast transitions in systems with edge illumination. TVs of the highest level use carpet lights (when the LEDs are located directly behind the matrix). This makes it possible to increase the uniformity of the backlight and introduce segmented illumination control, when the individual diodes responsible for the areas on the screen can dim the brightness depending on the scene on the screen. In fact, there are only 2 series of carpet lights - the 9th Philips series and the 9th Sony series. In the 9th LG series, there is also a carpet light, but its implementation is worse than the edge one in competitive solutions.
Uneven backlight.
Due to the fact that the LEDs are arranged at a certain frequency (scattering and many other factors contribute to it), in almost 100% of cases, LCD TVs with LED backlighting have uneven illumination (clouding) - when areas that should be black have a different gradation gray.The problem is partially solved by a segmented LED light.
1.2 Types of matrix LCD-TVs with LED-backlit.
I will not go into details of the formation of images of different types of matrices, and briefly describe their main advantages and disadvantages.a) IPS (only LG currently produces). Matrixes, which, in my opinion, are ideal for low and medium level TV.
Advantages: large viewing angles.
Disadvantages: high black level (~ 0.16 nits), long response time.
They are installed on LG 3–9 series TVs (that is, virtually everything, without division into levels), Philips 4, 6 series, Panasonic of different variations and many others.
b) S-PVA (manufactured by Samsung). Matrix TV class above.
Advantages: deeper black (0.05-0.1 nit, depending on the implementation of the backlight).
Installed on Samsung TV 7-8 series, Sony 7-8 series, Philips 7-8 series and some others.
c) UV²A (manufactured by Sharp). In my opinion, the most perfect type of matrix.
Advantages: corners are larger than those of S-PVA (but smaller than those of IPS). The deepest black level (0.02 - 0.06 nits)
Disadvantages: Sharp produces them in insufficient quantities.
Installed on Philips 9-series TVs and Sharp top series.
2. Plasma.
There are a lot of myths and delusions connected with this word. Any unknowing seller will surely tell you that the plasma is outdated. This is due to a set of stereotypes and problems that have taken place.The image is formed by the luminescence of the phosphor under the action of UV rays.
Each plasma cell is an independent light source, so the TV does not require lighting. Previously, plasma TVs had a very large thickness and cell size, so they were very cumbersome and the Full HD diagonal started from 50-60 ". Now the thickness of modern plasma TVs does not exceed 3-4 cm, and the diagonal starts from 42".
Plasma TVs do not have different types of matrixes with marketing names, but there are panel generations (the most perfect is the 15th).
Now the plasma is almost superseded by LCD-TVs and only 3 companies are engaged in its production: Panasonic, Samsung and LG (and only the first 2 have their own developments). This is due to the unprofitability of production, competition from LCD TVs and their popularization. But the plasma holds the first position in the large diagonals.
3. OLED.
Organic LEDs. Something average, between the first 2 technologies. The image is formed using self-emitting diodes that glow under the influence of an electric current. As in plasma, each cell is an independent source of light. So far there are only a few serial samples of such TVs at very high prices. Developments in this area are LG and Samsung.There are other types of televisions, such as projection laser televisions, but their development has already been discontinued.
Briefly about the advantages and disadvantages of each technology:
LCD:
Benefits:
- relatively low cost of production, which allows manufacturers to get quite a high profit and invest in production.
- The static method of imaging (without dithering) is good for displaying images and photos.
- Great for a static image and not afraid of it.
- LCD TVs have high brightness and low power consumption
disadvantages
- High black level (from 0.02 nits in a UV²A matrix with carpet backlighting up to 0.2 nits in IPS).
- Great response time
- Lack of volume and depth of the image
- Dynamic resolution without artificial tricks 300 - 700 lines.
Plasma
Benefits
- The overall depth of the image. In general, when delivering high-quality content, the image on the plasma is noticeably different from that in the LCD: it has greater depth and color saturation, has a pronounced effect of volume.
- Low black level (0.008 nits in 2012 Panasonic models).
- Have a dynamic resolution without artificial tricks of 1080 lines.
- Excellent for dynamic images (movies), well reveal high-quality content.
- Actually there is no response time.
- Free viewing angles
disadvantages
- It is not suitable for connecting to a computer because of the residual image
- Worse show photos (as the gradations are obtained by dithering)
- Large power consumption, not all models have high brightness.
- High production cost, low margin - it is becoming more and more difficult for manufacturers to stay afloat.
OLED
The newest imaging technology in televisions. Self-emitting organic LEDs are used. Like plasma, these are self-emission displays that do not require illumination.
Now only a few serial samples are released at a price ten times higher than similar LCD and plasma TVs, but LG promises that in 3 years OLED TVs of similar LCD and plasma diagonals will cost 1.5 times more.
Benefits:
- low response time and high contrast, as in plasma, since there are no mechanically rotating molecules and constant backlighting, as in the LCD.
- profitability
- wide viewing angles.
Disadvantages:
- different pixel degradation over time (just like in plasma, which results in residual images and pixel burnout). Now they are trying to compensate for it programmatically.
- Low service time: about 10,000 hours (for example, the LCD has 60,000 hours and the plasma has 100,000 thousand hours).
II Image Features
Choosing a new TV, I came to the conclusion that some characteristics of the image can be changed, some can not.Measured characteristics:
- Black level (MLL, Minimum luminescence level) - the black level that shows the TV when the signal is 0. [nit]
- Brightness - the level of brightness that shows the TV when it receives a 255 signal.
These 2 characteristics are measured together when a “chessboard” is displayed on the TV (ANSI method) - alternation of black and white areas. Calculates the brightness of each area, the arithmetic average of the brightness of black and white areas.
- Contrast. The difference between the arithmetic average of black and white areas when black areas are taken as a unit.
ANSI contrast of IPS matrices is ~ 1000: 1, S-PVA - 3500: 1, UV²A - 5000: 1, plasma - 12000: 1.
- Color accuracy (DeltaE, deviation from the standard). An input signal is applied, the output signal is measured. The greater the deviation - the less accurate color reproduction. It is believed that the naked eye is unable to notice a deviation of DeltaE <3, and zero indicates perfect color rendering.
- Viewing angles. The smaller the viewing angle of the matrix, the more distorted the color. The smallest angles are LCD S-PVA matrix. The largest - plasma panels.
- Dynamic resolution. As you know, almost all TVs have a static resolution of 1080 lines (1920x1080 pixels), but the dynamic resolution (what the TV shows when movement occurs on the screen) is often different. For this purpose, backlight flickering, frame interpolation and other tricks are introduced in LCD TVs.
Subjective characteristics
These include the volume of the image, which is formed by a combination of black level and color saturation, the “cinematicity” of the image, the effect of presence.
Thanks for attention.
If the article seems interesting, in the next part I will write about the choice of the diagonal, the 3D types, their practical difference, about the interpolation of the image and try to debunk some myths.
Source: https://habr.com/ru/post/162743/
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