Gene
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As we all know, brightness is an extremely important indicator for projectors. Recently in the projector market, especially in the home the projector on the market, in the Light Source Brightness this concept.
First of all, the concept of standard projector brightness refers to the brightness of the brightest white screen projected by the projector on a standardized ideal projection screen in an ideal environment. Among them, the ideal environment means that "the transmission of light from the lens to the projection screen does not cause any loss of brightness"; The meaning of "standardized ideal projection screen" is that the reflectance of the screen is 100%, the Angle of reflection does not have invalid scattering, and the size of the reflection screen exactly covers the projected picture. Obviously, this so-called ideal state of brightness measurement is not possible, the actual method is to use the environmental scattering coefficient, screen absorption coefficient to correct the measurement system error. At the same time, the brightness of the projector under the standard definition is generally consistent with the light flux measured at the lens.
Second, what is the Light Source Brightness? Simply put, it is the total brightness of visible light produced by the light source as part of the luminous body. If it is the blue laser fluorescence color wheel technology, then it is the total brightness of the blue laser; If mercury lamp Light Source, so in addition to the red, green, blue Light wavelength of energy, the Light Source Brightness also includes other wavelengths (though much lower the sensitivity of the eye to the latter). If it is a red, green and blue RGB LED light source, it is the sum of the luminance of the three primary colors.
Blue laser light source
Introduces the concept of above two Brightness, we can talk about Light Source between Brightness and Brightness projector "privacy". In the laser projector, Light Source Brightness basic is the Brightness of the blue laser combined. However, the light emitted by the blue laser generally appears on the projected picture after at least passing through "light transmission", "beam expansion", "dissipating spot", "fluorescent pink wheel", "original color wheel", "directional reflecting lens", "DMD" light valve and "projection lens composed of multiple groups of optical lenses and electro-mechanical structure". The Light Source Brightness and Brightness into projection at least after more than ten steps of processing in the middle. And each processing step will result in a decrease in brightness.
Let's look at some of the brightness losses:
First, glass lenses. The transmittance of normal glass is a little more than 80% (the white glass Windows in our buildings), and the transmittance of optical glass is more than 94%. But even with this high projection rate of glass, the total projection ability drops to 73 percent after five shots.
Second, DMD light valve working conditions. When DMD works, opening rate, transmittance, scattering rate, reflectance, system cleanliness, etc., all affect brightness transmission, and none of these data can reach 100% transmission brightness, so it can be seen that a DMD light valve has a great influence on product brightness.
Third, the Light Source Brightness, one of the largest loss point is actually a lot of people ignore the problem that the beam of Light to produce cross section shape and the difference between DMD Light valve lens shape. The DMD mirror is generally a 4:3, 16:9, and 16:10 rectangle. The beam section of the light source is generally round and oval. In the simplest case, a circular beam of light on a 4:3-shaped DMD is already less than two-thirds efficient, losing nearly 40% of its brightness at once.
Fourth, for the laser fluorescence color wheel technology, the efficiency of fluorescence transformation must also be considered: namely, the conversion efficiency from blue laser to green fluorescence, and from blue laser to red fluorescence. Among them, because of the energy of white light, green basically takes half, so the efficiency of green phosphor is a very big problem. For example, the quantum efficiency of most nitride green phosphors is between 70-90%.
Above all, assuming all optical system efficiency reached 100% of the ideal state of god completely, 5000 lumens Light Source Brightness of laser projector, can give an ideal Brightness also however 2300 + lumen (consider DMD90 % opening rate and Light beam cross section with DMD Light valve cover poor, 80% of efficiency of phosphor powder).
In fact, this is in the world where there is a perfect optical system, has been cited in front including "light transfer", "beam expander", "dispel spot", "the original colored wheel", "direction reflect lens", "more sets of optical lenses and electronic mechanical structure of the projection lens" a lot of optical structure, such as every optical lenses have transmittance, scattering rate, absorption rate, cleanliness and other indicators affecting brightness. The optical structure can make the projector's Light Source Brightness using level to make a folded in half. As a result, the projection Brightness is actually only Light Source Brightness around a third, if the determined using single chip DLP projection system, blue laser fluorescence color wheel system, projector Brightness could only Light Source Brightness of a quarter.
Finally, the most useful data for a projector is the ANSI brightness. The so-called ANSI brightness is actually the optimized brightness, which means a brightness when the color of the screen is normal. In the specific evaluation, we will take nine points of the screen to test. From a professional point of view, the ANSI brightness and maximum brightness will be more meaningful for our reference.
First of all, the concept of standard projector brightness refers to the brightness of the brightest white screen projected by the projector on a standardized ideal projection screen in an ideal environment. Among them, the ideal environment means that "the transmission of light from the lens to the projection screen does not cause any loss of brightness"; The meaning of "standardized ideal projection screen" is that the reflectance of the screen is 100%, the Angle of reflection does not have invalid scattering, and the size of the reflection screen exactly covers the projected picture. Obviously, this so-called ideal state of brightness measurement is not possible, the actual method is to use the environmental scattering coefficient, screen absorption coefficient to correct the measurement system error. At the same time, the brightness of the projector under the standard definition is generally consistent with the light flux measured at the lens.
Second, what is the Light Source Brightness? Simply put, it is the total brightness of visible light produced by the light source as part of the luminous body. If it is the blue laser fluorescence color wheel technology, then it is the total brightness of the blue laser; If mercury lamp Light Source, so in addition to the red, green, blue Light wavelength of energy, the Light Source Brightness also includes other wavelengths (though much lower the sensitivity of the eye to the latter). If it is a red, green and blue RGB LED light source, it is the sum of the luminance of the three primary colors.
Blue laser light source
Introduces the concept of above two Brightness, we can talk about Light Source between Brightness and Brightness projector "privacy". In the laser projector, Light Source Brightness basic is the Brightness of the blue laser combined. However, the light emitted by the blue laser generally appears on the projected picture after at least passing through "light transmission", "beam expansion", "dissipating spot", "fluorescent pink wheel", "original color wheel", "directional reflecting lens", "DMD" light valve and "projection lens composed of multiple groups of optical lenses and electro-mechanical structure". The Light Source Brightness and Brightness into projection at least after more than ten steps of processing in the middle. And each processing step will result in a decrease in brightness.
Let's look at some of the brightness losses:
First, glass lenses. The transmittance of normal glass is a little more than 80% (the white glass Windows in our buildings), and the transmittance of optical glass is more than 94%. But even with this high projection rate of glass, the total projection ability drops to 73 percent after five shots.
Second, DMD light valve working conditions. When DMD works, opening rate, transmittance, scattering rate, reflectance, system cleanliness, etc., all affect brightness transmission, and none of these data can reach 100% transmission brightness, so it can be seen that a DMD light valve has a great influence on product brightness.
Third, the Light Source Brightness, one of the largest loss point is actually a lot of people ignore the problem that the beam of Light to produce cross section shape and the difference between DMD Light valve lens shape. The DMD mirror is generally a 4:3, 16:9, and 16:10 rectangle. The beam section of the light source is generally round and oval. In the simplest case, a circular beam of light on a 4:3-shaped DMD is already less than two-thirds efficient, losing nearly 40% of its brightness at once.
Fourth, for the laser fluorescence color wheel technology, the efficiency of fluorescence transformation must also be considered: namely, the conversion efficiency from blue laser to green fluorescence, and from blue laser to red fluorescence. Among them, because of the energy of white light, green basically takes half, so the efficiency of green phosphor is a very big problem. For example, the quantum efficiency of most nitride green phosphors is between 70-90%.
Above all, assuming all optical system efficiency reached 100% of the ideal state of god completely, 5000 lumens Light Source Brightness of laser projector, can give an ideal Brightness also however 2300 + lumen (consider DMD90 % opening rate and Light beam cross section with DMD Light valve cover poor, 80% of efficiency of phosphor powder).
In fact, this is in the world where there is a perfect optical system, has been cited in front including "light transfer", "beam expander", "dispel spot", "the original colored wheel", "direction reflect lens", "more sets of optical lenses and electronic mechanical structure of the projection lens" a lot of optical structure, such as every optical lenses have transmittance, scattering rate, absorption rate, cleanliness and other indicators affecting brightness. The optical structure can make the projector's Light Source Brightness using level to make a folded in half. As a result, the projection Brightness is actually only Light Source Brightness around a third, if the determined using single chip DLP projection system, blue laser fluorescence color wheel system, projector Brightness could only Light Source Brightness of a quarter.
Finally, the most useful data for a projector is the ANSI brightness. The so-called ANSI brightness is actually the optimized brightness, which means a brightness when the color of the screen is normal. In the specific evaluation, we will take nine points of the screen to test. From a professional point of view, the ANSI brightness and maximum brightness will be more meaningful for our reference.
