abstract
This paper mainly introduces the following aspects of knowledge:
Principle of LCD projection technology;
What is open optical machinery and what is totally closed optical machinery;
Why is the fully enclosed optical mechanical system more advantageous;
1、 Principle of LCD projection technology
Liquid crystal display (LCD), namely liquid crystal display technology, uses the photoelectric effect of liquid crystal molecules to change the light transmittance or reflectivity of the liquid crystal unit to achieve picture display.
The conventional light sources of LCD projector include metal halide lamp, UHP (cold light source) and LED lamp. The liquid crystal panel is used as the light control layer, and the change of the liquid crystal transparency of the corresponding pixels of the panel is controlled by the system electrical signal, so as to control the light intensity of the liquid crystal to produce different gray and color images. Finally, the images are projected on the display area through the lens.
LCD projector is divided into three LCD, single LCD projector.
1. Three chip LCD projector
The three LCD optical system consists of three LCD panels. The white light emitted by the light source is divided into red light, green light and blue light through two filters, and then projected on three corresponding liquid crystal panels respectively. After mixing the three kinds of primary light through the middle concentrating prism, different color images are projected（ Statement: the figure below is from the Internet, not original)
2. Monolithic LCD projection
The monolithic LCD optical system consists of a liquid crystal panel. The white light emitted by the light source passes through the Fresnel lens 1 into regular parallel light, then passes through the polarizer to form polarized light, and after passing through the LCD panel in the middle, it transmits image light of different colors, which is focused and enhanced by the Fresnel lens 2. Finally, the projected display screen is projected through the total reflection mirror.
2. What is an open optical machine and what is a fully enclosed optical machine?
1. Open LCD Optical Machine
Early LCD projections generally adopted an open opto-mechanical design due to the need for cost and heat dissipation control.
The brightness of the projector is directly proportional to the power of the light source. When the brightness is increased, a high-power light source is inevitably required, and the high-power light source brings higher heat generation. The liquid crystal panel (HTPS) is composed of high-temperature polysilicon. This polymer liquid crystal material will accelerate aging if it is operated at high temperature for a long time. At the same time, the glass of the HTPS substrate is also prone to changes in optical properties.
In order to reduce the temperature of HTPS, slow down its aging speed, and take into account cost control, the optical machines of early liquid crystal projectors all adopted an open structure design, that is, the heat dissipation air path inside the optical machine communicates with the outside world, and the outside air is sucked in through the cooling fan. After the heat source is exported again, the purpose of reducing the internal temperature of the optical engine is achieved. (The heat source refers to the heat generated by the light loss in the light source and the optical path and the heating of the circuit board)
2. Fully enclosed LCD light machine
The closed optical machine design is the main development direction of the LCD projector optical machine. The biggest feature of the closed optical machine is that the optical path of the optical machine is a closed structure. It is assembled in a dust-free workshop that reaches at least 10,000 dustproof standards to ensure The internal air meets the dust-free standard, and the optical path of the optical machine is no longer connected to the outside after the assembly is completed. The heat dissipation of the light source is treated separately outside the optical engine, and the temperature of the HTPS is reduced through the internal air circulation + clever heat dissipation design inside the optical path of the optical engine. The enclosed optical engine solves the dustproof and also takes into account the heat dissipation requirements of HTPS, which is a more advanced design.
Third, why the fully enclosed optical machine has more advantages
The heat dissipation air path inside the open optical machine is connected to the outside world and circulates heat with the outside air. However, due to the existence of a certain amount of suspended particles (dust) in the air, dust will also enter the light path and adhere to it while dissipating heat. To the HTPS and the lens mirror surface, thereby affecting the light passing rate and the heat dissipation effect of the HTPS, causing the "black spot" problem of the projection screen, and ultimately leading to poor projection effects and shortening the service life of the HTPS. (The root cause of the problem of yellow and black spots on the projection screen)
In order to prevent dust, manufacturers use double filters, pleated filters, multiple filters, etc. to reduce the passing rate of dust. Although it has a good dust-proof effect, it is required to remove and clean the dust-proof filter regularly to remove dust and dust. , Users need regular maintenance. In addition, LCD projections with an open design are prone to light leakage. When viewing a movie in a darker environment, light leaks through the gaps in the fuselage, which makes the product as a whole full of cheap feeling.
The inside of the fully enclosed optical machine is isolated from the outside world. The optical path is a closed and independent structure, and is assembled in a dust-free workshop to eliminate the influence of dust on the glass of the liquid crystal panel (HTPS) and HTPS substrate. Its excellent dustproof ability can prevent LCD projection from turning yellow and displaying "black spots" after long-term use, and prolong the service life of the projection. At the same time, the light leakage problem of the product is solved. We can use it normally after purchasing the projector, and there is no need to do other maintenance actions such as regular dust removal.
In summary, the advantages of the fully enclosed optomechanical design are obvious. If we have the need to purchase LCD projection, it is recommended to choose projection products with enclosed optical machines first, so that we can get a better product experience.
This paper mainly introduces the following aspects of knowledge:
Principle of LCD projection technology;
What is open optical machinery and what is totally closed optical machinery;
Why is the fully enclosed optical mechanical system more advantageous;
1、 Principle of LCD projection technology
Liquid crystal display (LCD), namely liquid crystal display technology, uses the photoelectric effect of liquid crystal molecules to change the light transmittance or reflectivity of the liquid crystal unit to achieve picture display.
The conventional light sources of LCD projector include metal halide lamp, UHP (cold light source) and LED lamp. The liquid crystal panel is used as the light control layer, and the change of the liquid crystal transparency of the corresponding pixels of the panel is controlled by the system electrical signal, so as to control the light intensity of the liquid crystal to produce different gray and color images. Finally, the images are projected on the display area through the lens.
LCD projector is divided into three LCD, single LCD projector.
1. Three chip LCD projector
The three LCD optical system consists of three LCD panels. The white light emitted by the light source is divided into red light, green light and blue light through two filters, and then projected on three corresponding liquid crystal panels respectively. After mixing the three kinds of primary light through the middle concentrating prism, different color images are projected（ Statement: the figure below is from the Internet, not original)
2. Monolithic LCD projection
The monolithic LCD optical system consists of a liquid crystal panel. The white light emitted by the light source passes through the Fresnel lens 1 into regular parallel light, then passes through the polarizer to form polarized light, and after passing through the LCD panel in the middle, it transmits image light of different colors, which is focused and enhanced by the Fresnel lens 2. Finally, the projected display screen is projected through the total reflection mirror.
2. What is an open optical machine and what is a fully enclosed optical machine?
1. Open LCD Optical Machine
Early LCD projections generally adopted an open opto-mechanical design due to the need for cost and heat dissipation control.
The brightness of the projector is directly proportional to the power of the light source. When the brightness is increased, a high-power light source is inevitably required, and the high-power light source brings higher heat generation. The liquid crystal panel (HTPS) is composed of high-temperature polysilicon. This polymer liquid crystal material will accelerate aging if it is operated at high temperature for a long time. At the same time, the glass of the HTPS substrate is also prone to changes in optical properties.
In order to reduce the temperature of HTPS, slow down its aging speed, and take into account cost control, the optical machines of early liquid crystal projectors all adopted an open structure design, that is, the heat dissipation air path inside the optical machine communicates with the outside world, and the outside air is sucked in through the cooling fan. After the heat source is exported again, the purpose of reducing the internal temperature of the optical engine is achieved. (The heat source refers to the heat generated by the light loss in the light source and the optical path and the heating of the circuit board)
2. Fully enclosed LCD light machine
The closed optical machine design is the main development direction of the LCD projector optical machine. The biggest feature of the closed optical machine is that the optical path of the optical machine is a closed structure. It is assembled in a dust-free workshop that reaches at least 10,000 dustproof standards to ensure The internal air meets the dust-free standard, and the optical path of the optical machine is no longer connected to the outside after the assembly is completed. The heat dissipation of the light source is treated separately outside the optical engine, and the temperature of the HTPS is reduced through the internal air circulation + clever heat dissipation design inside the optical path of the optical engine. The enclosed optical engine solves the dustproof and also takes into account the heat dissipation requirements of HTPS, which is a more advanced design.
Third, why the fully enclosed optical machine has more advantages
The heat dissipation air path inside the open optical machine is connected to the outside world and circulates heat with the outside air. However, due to the existence of a certain amount of suspended particles (dust) in the air, dust will also enter the light path and adhere to it while dissipating heat. To the HTPS and the lens mirror surface, thereby affecting the light passing rate and the heat dissipation effect of the HTPS, causing the "black spot" problem of the projection screen, and ultimately leading to poor projection effects and shortening the service life of the HTPS. (The root cause of the problem of yellow and black spots on the projection screen)
In order to prevent dust, manufacturers use double filters, pleated filters, multiple filters, etc. to reduce the passing rate of dust. Although it has a good dust-proof effect, it is required to remove and clean the dust-proof filter regularly to remove dust and dust. , Users need regular maintenance. In addition, LCD projections with an open design are prone to light leakage. When viewing a movie in a darker environment, light leaks through the gaps in the fuselage, which makes the product as a whole full of cheap feeling.
The inside of the fully enclosed optical machine is isolated from the outside world. The optical path is a closed and independent structure, and is assembled in a dust-free workshop to eliminate the influence of dust on the glass of the liquid crystal panel (HTPS) and HTPS substrate. Its excellent dustproof ability can prevent LCD projection from turning yellow and displaying "black spots" after long-term use, and prolong the service life of the projection. At the same time, the light leakage problem of the product is solved. We can use it normally after purchasing the projector, and there is no need to do other maintenance actions such as regular dust removal.
In summary, the advantages of the fully enclosed optomechanical design are obvious. If we have the need to purchase LCD projection, it is recommended to choose projection products with enclosed optical machines first, so that we can get a better product experience.
