Lighting has an important influence on human activities. In ancient times, people used oil, candles, etc. to obtain light, and even used fireflies that could be illuminated at night as a light source.
During the Jin Dynasty, there was a man named Che Yu who learned from time to time and didn't want to let it go. However, because the family is very poor, I can't buy the oil of the starting light. So every summer night, he catches many fireflies and puts them in a small hole. They use the light of fireflies to read the book. As a result, the rut of hard learning finally came out, and finally the official to the Department of the Book. In addition, the ancient book "Ancient and Modern Secret Garden" has also recorded: "The sheep's bladder is inflated and dried, and more than a hundred pieces of fireflies are attached to the bottom of the foot. The fish are not limited in size, each rushing to the light, gathering without moving, catching There must be more." This is the story of fishing with the light of fireflies.
The firefly has an illuminator at the end of the body that consists of three parts: the skin, the luminescent cells, and the reflective layer. The light emitted by the luminescent cells appears brighter due to the reflection of the reflective layer. The main substances in luminescent cells are luciferin and luciferase. Insect fluorescein is the source of light energy, and luciferase is the catalyst. When the firefly starts to move, the breathing speeds up, the body absorbs a lot of oxygen, and oxygen enters the luminescent cell through the small air tube. Under the catalysis of luciferase, the luciferin begins to produce an oxidation reaction, which causes the belly to emit light. Due to the difference in fire rhythm of fireflies, they form a "small star" that flashes when it is bright.
Since the efficiency of luciferin conversion energy is very high, only about 2%-10% of the energy is wasted on the heat energy, and the rest of the energy is used to emit light. Therefore, the firefly's luminescence can be called a "cold light", physics. The home thinks this is a very ideal light. Incandescent bulb
As civilization progresses, humans try various methods to obtain a light source.
Until October 21, 1879, in a dusty laboratory in New Jersey, USA, Edison sealed a very thin carbon fiber in a glass bubble and used a vacuum pump to pump the air out of the glass bubble. The voltage is supplied steadily, turning the filament into a very stable bright light source, and the era of electric lighting has come.
Although the form, shape, and color of an incandescent light bulb are innumerable, the composition includes a lamp cap, a filament, a gas filled in the bulb, and a bulb that is insulated from the outside. The lamp cap is the device used to connect the bulb to the lamp holder, and the filament is the component that is actually used to illuminate the bulb. In general, the higher the operating temperature of the filament, the greater the portion of the energy produced in the visible region. The filament was first produced from carbon, but all of them were later replaced with tungsten wire because the melting point of tungsten is high, it is not easily damaged, and the spectral characteristics are better, and it has the resistance to heat and cold. The gas to be filled is usually an inert gas, which can apply pressure to the filament to prevent evaporation of the filament. The light bulb is used to isolate it from the outside world. If it is not isolated, the filament will quickly react with the oxygen in the air and burn.
When a filament with a large resistance passes an increasing current, the filament begins to heat up and illuminate until it reaches an incandescent color. Incandescent bulbs have since been modified to suit specific needs, so they can be subdivided into general-purpose lamps, high-voltage and low-voltage lamps, halogen lamps, and infrared lamps. But in general, incandescent bulbs can not meet the needs of human beings as large rooms or large-scale space lighting equipment, but the invention of electric lights has occupied a very important position in the history of human science for more than a hundred years. fluorescent lamp
Fluorescent lamps (or fluorescent lamps) can be said to be a very important invention of indoor lighting. Nowadays, most of the nighttime indoor lighting in the world uses fluorescent lamps. Compared with the traditional light bulb, the fluorescent tube has the advantages of long service life, high luminous efficiency, large illumination area, and can be adjusted into different light colors.
The structure of a fluorescent lamp is usually a long cylindrical tube containing a very small amount of mercury and a small amount of inert gas (argon or helium). After being energized, the electrodes at both ends of the lamp cause high-voltage discharge, and the inert gas in the free tube generates an arc, which excites the mercury vapor to emit ultraviolet light having a shorter wavelength. The phosphor applied to the inner wall of the tube absorbs ultraviolet light and is converted into visible light. If you change the type of phosphor, you can get lighting suitable for different occasions, such as cool white light suitable for office and factory, suitable for warm light in warm social environment, and fluorescent lamps for general households, schools and other occasions.
The use of fluorescent lamps meets the needs of most human occasions. Although various types of electric lamps are still under development, as of the 20th century, it is still impossible to develop inventions that are more in line with human needs than fluorescent lamps. Although fluorescent lamps have many advantages, one of the biggest drawbacks is that fluorescent tubes consume a lot of power, and most of the electrical energy is consumed in thermal energy. In addition, the mercury in the lamp has the problem of polluting the environment. Therefore, it is always the task of scientists and the business community to seek new illumination sources. led
Light-emitting diodes that began to develop in the late 20th century will bring dawn to the future. In 1996, based on GaN blue light-emitting diodes, Nichia Corporation of Japan developed a yellow LED to excite yttrium aluminum garnet phosphors to produce yellow fluorescence. The resulting yellow fluorescence is then mixed with blue light to produce white light (blue LED with YAG). Phosphor) has opened the curtain for LEDs entering the lighting market.
The main structure of a white light-emitting diode consists of a diode at the bottom, a phosphor coated on a diode or a lampshade, and a lampshade that isolates the outside. When the bottom diode (usually a semiconductor material) is excited by electrical energy, an electron-to-hole pair is generated. When the electron is recombined with the hole, the diode emits a first emitted light (ultraviolet light or blue light). The first emitted light can be absorbed by the phosphor and converted into a second emitted light (visible wavelength range), and when the first emitted light that is not absorbed by the phosphor and the second emitted light emitted by the phosphor are mixed, White light.
With the use of different phosphors, LEDs can also have different colors of light or warm colors like fluorescent tubes. In addition, after years of research and development, it has been found that the use of high-efficiency ultraviolet light-emitting diodes as the light source is the future choice for white light-emitting diodes to become lighting devices. Therefore, how to develop high-efficiency ultraviolet light-emitting diodes and phosphors suitable for ultraviolet light is the goal of everyone today.
With the advancement of LED technology, the application of white LEDs has gradually developed, including indicator lights, portable flashlights, LCD screen backlights, automotive instrumentation and interior lights. The industry believes that in the next 10 years, white light-emitting diodes will be widely used in lighting, becoming the dawn of human lighting in the 21st century.
During the Jin Dynasty, there was a man named Che Yu who learned from time to time and didn't want to let it go. However, because the family is very poor, I can't buy the oil of the starting light. So every summer night, he catches many fireflies and puts them in a small hole. They use the light of fireflies to read the book. As a result, the rut of hard learning finally came out, and finally the official to the Department of the Book. In addition, the ancient book "Ancient and Modern Secret Garden" has also recorded: "The sheep's bladder is inflated and dried, and more than a hundred pieces of fireflies are attached to the bottom of the foot. The fish are not limited in size, each rushing to the light, gathering without moving, catching There must be more." This is the story of fishing with the light of fireflies.
The firefly has an illuminator at the end of the body that consists of three parts: the skin, the luminescent cells, and the reflective layer. The light emitted by the luminescent cells appears brighter due to the reflection of the reflective layer. The main substances in luminescent cells are luciferin and luciferase. Insect fluorescein is the source of light energy, and luciferase is the catalyst. When the firefly starts to move, the breathing speeds up, the body absorbs a lot of oxygen, and oxygen enters the luminescent cell through the small air tube. Under the catalysis of luciferase, the luciferin begins to produce an oxidation reaction, which causes the belly to emit light. Due to the difference in fire rhythm of fireflies, they form a "small star" that flashes when it is bright.
Since the efficiency of luciferin conversion energy is very high, only about 2%-10% of the energy is wasted on the heat energy, and the rest of the energy is used to emit light. Therefore, the firefly's luminescence can be called a "cold light", physics. The home thinks this is a very ideal light. Incandescent bulb
As civilization progresses, humans try various methods to obtain a light source.
Until October 21, 1879, in a dusty laboratory in New Jersey, USA, Edison sealed a very thin carbon fiber in a glass bubble and used a vacuum pump to pump the air out of the glass bubble. The voltage is supplied steadily, turning the filament into a very stable bright light source, and the era of electric lighting has come.
Although the form, shape, and color of an incandescent light bulb are innumerable, the composition includes a lamp cap, a filament, a gas filled in the bulb, and a bulb that is insulated from the outside. The lamp cap is the device used to connect the bulb to the lamp holder, and the filament is the component that is actually used to illuminate the bulb. In general, the higher the operating temperature of the filament, the greater the portion of the energy produced in the visible region. The filament was first produced from carbon, but all of them were later replaced with tungsten wire because the melting point of tungsten is high, it is not easily damaged, and the spectral characteristics are better, and it has the resistance to heat and cold. The gas to be filled is usually an inert gas, which can apply pressure to the filament to prevent evaporation of the filament. The light bulb is used to isolate it from the outside world. If it is not isolated, the filament will quickly react with the oxygen in the air and burn.
When a filament with a large resistance passes an increasing current, the filament begins to heat up and illuminate until it reaches an incandescent color. Incandescent bulbs have since been modified to suit specific needs, so they can be subdivided into general-purpose lamps, high-voltage and low-voltage lamps, halogen lamps, and infrared lamps. But in general, incandescent bulbs can not meet the needs of human beings as large rooms or large-scale space lighting equipment, but the invention of electric lights has occupied a very important position in the history of human science for more than a hundred years. fluorescent lamp
Fluorescent lamps (or fluorescent lamps) can be said to be a very important invention of indoor lighting. Nowadays, most of the nighttime indoor lighting in the world uses fluorescent lamps. Compared with the traditional light bulb, the fluorescent tube has the advantages of long service life, high luminous efficiency, large illumination area, and can be adjusted into different light colors.
The structure of a fluorescent lamp is usually a long cylindrical tube containing a very small amount of mercury and a small amount of inert gas (argon or helium). After being energized, the electrodes at both ends of the lamp cause high-voltage discharge, and the inert gas in the free tube generates an arc, which excites the mercury vapor to emit ultraviolet light having a shorter wavelength. The phosphor applied to the inner wall of the tube absorbs ultraviolet light and is converted into visible light. If you change the type of phosphor, you can get lighting suitable for different occasions, such as cool white light suitable for office and factory, suitable for warm light in warm social environment, and fluorescent lamps for general households, schools and other occasions.
The use of fluorescent lamps meets the needs of most human occasions. Although various types of electric lamps are still under development, as of the 20th century, it is still impossible to develop inventions that are more in line with human needs than fluorescent lamps. Although fluorescent lamps have many advantages, one of the biggest drawbacks is that fluorescent tubes consume a lot of power, and most of the electrical energy is consumed in thermal energy. In addition, the mercury in the lamp has the problem of polluting the environment. Therefore, it is always the task of scientists and the business community to seek new illumination sources. led
Light-emitting diodes that began to develop in the late 20th century will bring dawn to the future. In 1996, based on GaN blue light-emitting diodes, Nichia Corporation of Japan developed a yellow LED to excite yttrium aluminum garnet phosphors to produce yellow fluorescence. The resulting yellow fluorescence is then mixed with blue light to produce white light (blue LED with YAG). Phosphor) has opened the curtain for LEDs entering the lighting market.
The main structure of a white light-emitting diode consists of a diode at the bottom, a phosphor coated on a diode or a lampshade, and a lampshade that isolates the outside. When the bottom diode (usually a semiconductor material) is excited by electrical energy, an electron-to-hole pair is generated. When the electron is recombined with the hole, the diode emits a first emitted light (ultraviolet light or blue light). The first emitted light can be absorbed by the phosphor and converted into a second emitted light (visible wavelength range), and when the first emitted light that is not absorbed by the phosphor and the second emitted light emitted by the phosphor are mixed, White light.
With the use of different phosphors, LEDs can also have different colors of light or warm colors like fluorescent tubes. In addition, after years of research and development, it has been found that the use of high-efficiency ultraviolet light-emitting diodes as the light source is the future choice for white light-emitting diodes to become lighting devices. Therefore, how to develop high-efficiency ultraviolet light-emitting diodes and phosphors suitable for ultraviolet light is the goal of everyone today.
With the advancement of LED technology, the application of white LEDs has gradually developed, including indicator lights, portable flashlights, LCD screen backlights, automotive instrumentation and interior lights. The industry believes that in the next 10 years, white light-emitting diodes will be widely used in lighting, becoming the dawn of human lighting in the 21st century.
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