"Let there be light": how did the backlighting of electronic devices evolve
The screens of many tablets and smartphones are based on LEDs, the radiation from which forms the image and at the same time plays the role of backlighting. But there are devices that do not have a "natural glow", such as electronic readers.
Electronic paper uses capsule balls filled with black and white granules that float upward in a clear liquid when a charge is applied to a cell. Such a screen can be clearly seen in the sun, but it is impossible to read from it in complete darkness, since by its properties it resembles ordinary paper.
Since these technologies - LED screens and electronic inks - have different working principles, their development has gone in different ways. We will describe further how the technologies of the backlighting of readers and LED displays evolved.
Our mega review on GT for ONYX BOOX Cleopatra 3 (with adjustable backlight heat)
It is believed that the history of modern displays originates in 1897, when Karl Ferdinand Braun (Karl Ferdinand Braun), a German physicist and Nobel Prize winner, created the first electron-beam device with a vacuum tube, the flow of electrons which formed images in a collision with a special screen .
Later in 1907, British researcher Henry Joseph Round (Henry Joseph Round) discovered the property of electroluminescence - a natural phenomenon, which later will form the basis of LED-technology. At the same time, the Russian scientist Boris Rosing issued a patent for the "method of electrical transmission of images." And in the period from 1925 to 1928, Scottish engineer John Logie Baird held a series of presentations, which resulted in the possibility of drawing faces of people and moving objects using a cathode ray tube. Also in 1939, Byrd showed color television based on CRT. The picture was formed by a disk of color filters, rotating in front of the screen.
Twenty years later, in the 61st year of the 20th century, Robert Bayard (Robert. Biard) and Gary Pittman (Gary Pittman) of Texas Instruments patented an infrared diode, the radiation of which was invisible to the human eye (the radiation produced gallium arsenide). A year later, American scientist Nick Holonyack invented the first LED, the light of which was visible. After that, Nick got the nickname "father of LED."
In 1964, the first LCD display and plasma panel (PDP) were invented . Further developments in the field of LCD-technologies led to the creation of the first LCD-watch by James Fergason by James Fergason. As for the plasma panels, they did not become particularly popular until the 90s, until digital technologies became more common.
Some time later (in the late 80s), Eastman Kodak researchers developed an OLED (organic light-emitting diode) technology based on organic light-emitting diodes . OLED allowed you to look at the display from any angle without loss of image quality.
Later, it developed into AMOLED technology, which increased the resolution and improved the color reproduction of OLED displays. To date, there are screens versions of Super AMOLED, HD Super AMOLED, Super AMOLED Advanced, and others, which are used in mobile devices (smartphones, tablets) and differ from each other in the features of the location of touch sensors. OLED screens are found in devices like Google Pixel 2, Samsung Galaxy S8 and many others.
The screen of the e-reader is clearly visible in the sun, because it resembles paper in its qualities - the brighter the light source, the clearer and more contrasting the text. However, it is impossible to read from it in complete darkness - it requires a third-party light source, for example, a desk lamp (or a cover with a lamp that some companies offer).
However, this reduces the portability of the gadget or (in the case of a case) adds another device, the charge of which you need to worry about. Therefore, developers of electronic readers began to create solutions that would highlight the screen in a dark room.
The first step in this direction was made at Sony. In 2008, the company introduced the PRS-700 reader with front-lit technology. Sony engineers positioned the LED lights that illuminated the display at the edges of the screen. Since the technology was new, the Japanese company failed to implement it correctly. The screen was illuminated unevenly, and its bluish tint interfered with reading. Also, the device had a fairly high cost - $ 400 - so it sold poorly. The company has received a huge number of negative reviews from its customers, because it has sworn to add lighting to subsequent devices.
For a long time, nothing like this appeared again. But in 2012, Barnes and Noble presented Simple Touch with Glowlight technology, which they bought from Flex Lighting. Instead of directing the light from the sides, as Sony did, B & N arranged the diodes, which shone from top to bottom, at the top of the screen. It also became possible to control the intensity of the backlight, so as not to disturb others when reading at night.
At the same time, the technology turned out to be energy efficient. Eight LEDs were used to illuminate the 6-inch screen. At that time, the Nook Simple Touch demanded a charge once every two months, and the addition of LEDs did not greatly affect the duration of the work. How did the lights, you can see in this video .
Immediately after Barnes and Noble - October 1, 2012 - Amazon presented its reading room with light. The product was called Amazon Kindle Paperwhite . The Paperwhite screen is similar to a sandwich and consists of three layers: an E Ink display and a capacitive touchscreen, on top of which a “light guide” is located (the Amazon team calls it “fiber optic made in the form of a sheet of paper”). In the lower part of the device, four LEDs are installed, the radiation from which is scattered by the fiber along the entire screen.
At the same time as Amazon, a reader with a similar technology was released by ONYX BOOX - the model was named Aurora (later on, Amazon and ONYX were joined by Kobo with the product Glo). It was the first (officially submitted) reader in Russia with the E Ink Pearl HD screen and the MOON Light backlight function. Aurora has become one of the most popular readers in Russia and the best-selling ONYX reader - the device won the “Product of the Year” award as the best gadget for reading electronic literature.
ONYX BOOX i62ML Aurora
The MOON Light backlight also uses the reflective method of light distribution when the light guide layer is placed above the screen. The LEDs are directed to the end of the fiber, and the light is refracted toward the screen. It is then absorbed by dark symbols, reflected from light surfaces and reaches the eye. This creates the impression that the text displayed on the display is illuminated by an external light source.
As neuroscientist George Brainard of Thomas Jefferson University notes, blue light prevents the production of melatonin, which regulates sleep, in the body. In order for the reader's backlighting to have less impact on the reader's health, ONYX developed MOON Light + technology. It uses two rows of LEDs: cold and warm colors, the brightness of which is independently controlled. This allows you to choose a warmer shade of light when reading at night, and when reading during the day - colder.
A little about the technology of electronic books ONYX BOOX
The first reader in Russia with the ability to adjust the “warmth” of the backlight was ONYX BOOX Cleopatra 3 (our mega review on the GT ). Model Cleopatra 3 has a touchscreen 6.8-inch E Ink Carta screen with a resolution of 1080x1440 pixels. Eight “cold” and seven “warm” diodes are responsible for adjusting the color scheme, the backlight intensity of which is controlled by two “sliders” in the settings. There is also a function SNOW Field, reducing the number of artifacts in the partial redrawing of images.
Solutions with different modes of illumination develop and other manufacturers of readers. Recently, Kobo, a reader of Aura One, presented its product with the ability to adjust the backlight tint. The device also has LEDs with white-blue and yellowish lighting.
It is safe to say that the screen backlighting technology will continue to improve as new e-paper-based solutions are emerging, such as readers with flexible E Ink screens. Time will show how the transmission of light from the source to the display in such solutions will be realized.
PS This week we published a detailed review on the ONYX BOOX Cleopatra 3 reader, in which we paid attention to the appearance of the device, its performance and interface.
PPS Other reviews of ONYX BOOX readers:
Electronic paper uses capsule balls filled with black and white granules that float upward in a clear liquid when a charge is applied to a cell. Such a screen can be clearly seen in the sun, but it is impossible to read from it in complete darkness, since by its properties it resembles ordinary paper.
Since these technologies - LED screens and electronic inks - have different working principles, their development has gone in different ways. We will describe further how the technologies of the backlighting of readers and LED displays evolved.
Our mega review on GT for ONYX BOOX Cleopatra 3 (with adjustable backlight heat)
Display Evolution
It is believed that the history of modern displays originates in 1897, when Karl Ferdinand Braun (Karl Ferdinand Braun), a German physicist and Nobel Prize winner, created the first electron-beam device with a vacuum tube, the flow of electrons which formed images in a collision with a special screen .
Later in 1907, British researcher Henry Joseph Round (Henry Joseph Round) discovered the property of electroluminescence - a natural phenomenon, which later will form the basis of LED-technology. At the same time, the Russian scientist Boris Rosing issued a patent for the "method of electrical transmission of images." And in the period from 1925 to 1928, Scottish engineer John Logie Baird held a series of presentations, which resulted in the possibility of drawing faces of people and moving objects using a cathode ray tube. Also in 1939, Byrd showed color television based on CRT. The picture was formed by a disk of color filters, rotating in front of the screen.
Twenty years later, in the 61st year of the 20th century, Robert Bayard (Robert. Biard) and Gary Pittman (Gary Pittman) of Texas Instruments patented an infrared diode, the radiation of which was invisible to the human eye (the radiation produced gallium arsenide). A year later, American scientist Nick Holonyack invented the first LED, the light of which was visible. After that, Nick got the nickname "father of LED."
In 1964, the first LCD display and plasma panel (PDP) were invented . Further developments in the field of LCD-technologies led to the creation of the first LCD-watch by James Fergason by James Fergason. As for the plasma panels, they did not become particularly popular until the 90s, until digital technologies became more common.
Some time later (in the late 80s), Eastman Kodak researchers developed an OLED (organic light-emitting diode) technology based on organic light-emitting diodes . OLED allowed you to look at the display from any angle without loss of image quality.
Later, it developed into AMOLED technology, which increased the resolution and improved the color reproduction of OLED displays. To date, there are screens versions of Super AMOLED, HD Super AMOLED, Super AMOLED Advanced, and others, which are used in mobile devices (smartphones, tablets) and differ from each other in the features of the location of touch sensors. OLED screens are found in devices like Google Pixel 2, Samsung Galaxy S8 and many others.
The development of screen backlighting of e-books
The screen of the e-reader is clearly visible in the sun, because it resembles paper in its qualities - the brighter the light source, the clearer and more contrasting the text. However, it is impossible to read from it in complete darkness - it requires a third-party light source, for example, a desk lamp (or a cover with a lamp that some companies offer).
However, this reduces the portability of the gadget or (in the case of a case) adds another device, the charge of which you need to worry about. Therefore, developers of electronic readers began to create solutions that would highlight the screen in a dark room.
The first step in this direction was made at Sony. In 2008, the company introduced the PRS-700 reader with front-lit technology. Sony engineers positioned the LED lights that illuminated the display at the edges of the screen. Since the technology was new, the Japanese company failed to implement it correctly. The screen was illuminated unevenly, and its bluish tint interfered with reading. Also, the device had a fairly high cost - $ 400 - so it sold poorly. The company has received a huge number of negative reviews from its customers, because it has sworn to add lighting to subsequent devices.
For a long time, nothing like this appeared again. But in 2012, Barnes and Noble presented Simple Touch with Glowlight technology, which they bought from Flex Lighting. Instead of directing the light from the sides, as Sony did, B & N arranged the diodes, which shone from top to bottom, at the top of the screen. It also became possible to control the intensity of the backlight, so as not to disturb others when reading at night.
At the same time, the technology turned out to be energy efficient. Eight LEDs were used to illuminate the 6-inch screen. At that time, the Nook Simple Touch demanded a charge once every two months, and the addition of LEDs did not greatly affect the duration of the work. How did the lights, you can see in this video .
Immediately after Barnes and Noble - October 1, 2012 - Amazon presented its reading room with light. The product was called Amazon Kindle Paperwhite . The Paperwhite screen is similar to a sandwich and consists of three layers: an E Ink display and a capacitive touchscreen, on top of which a “light guide” is located (the Amazon team calls it “fiber optic made in the form of a sheet of paper”). In the lower part of the device, four LEDs are installed, the radiation from which is scattered by the fiber along the entire screen.
At the same time as Amazon, a reader with a similar technology was released by ONYX BOOX - the model was named Aurora (later on, Amazon and ONYX were joined by Kobo with the product Glo). It was the first (officially submitted) reader in Russia with the E Ink Pearl HD screen and the MOON Light backlight function. Aurora has become one of the most popular readers in Russia and the best-selling ONYX reader - the device won the “Product of the Year” award as the best gadget for reading electronic literature.
ONYX BOOX i62ML Aurora
The MOON Light backlight also uses the reflective method of light distribution when the light guide layer is placed above the screen. The LEDs are directed to the end of the fiber, and the light is refracted toward the screen. It is then absorbed by dark symbols, reflected from light surfaces and reaches the eye. This creates the impression that the text displayed on the display is illuminated by an external light source.
The future of reader lighting technology
As neuroscientist George Brainard of Thomas Jefferson University notes, blue light prevents the production of melatonin, which regulates sleep, in the body. In order for the reader's backlighting to have less impact on the reader's health, ONYX developed MOON Light + technology. It uses two rows of LEDs: cold and warm colors, the brightness of which is independently controlled. This allows you to choose a warmer shade of light when reading at night, and when reading during the day - colder.
A little about the technology of electronic books ONYX BOOX
The first reader in Russia with the ability to adjust the “warmth” of the backlight was ONYX BOOX Cleopatra 3 (our mega review on the GT ). Model Cleopatra 3 has a touchscreen 6.8-inch E Ink Carta screen with a resolution of 1080x1440 pixels. Eight “cold” and seven “warm” diodes are responsible for adjusting the color scheme, the backlight intensity of which is controlled by two “sliders” in the settings. There is also a function SNOW Field, reducing the number of artifacts in the partial redrawing of images.
Solutions with different modes of illumination develop and other manufacturers of readers. Recently, Kobo, a reader of Aura One, presented its product with the ability to adjust the backlight tint. The device also has LEDs with white-blue and yellowish lighting.
It is safe to say that the screen backlighting technology will continue to improve as new e-paper-based solutions are emerging, such as readers with flexible E Ink screens. Time will show how the transmission of light from the source to the display in such solutions will be realized.
PS This week we published a detailed review on the ONYX BOOX Cleopatra 3 reader, in which we paid attention to the appearance of the device, its performance and interface.
PPS Other reviews of ONYX BOOX readers:
Source: https://habr.com/ru/post/409771/