The so-called lumen simply refers to the brightness of a candle at a distance of one meter (1 m = 1 m). The luminous efficiency of an ordinary 40-watt incandescent bulb is about 0/0 lumen per watt/kloc, so it can emit 400 lumens of light. A 40-watt incandescent lamp has a luminous flux of 340 lumens at 220 volts. Luminous flux is the ability to describe the intensity of visual response produced by light source radiation in unit time, and the unit is lumen, also called brightness. The unit of projector luminous flux is ANSI lumens, which is the standard for measuring projector luminous flux formulated by American National Standardization Association. It measures the illuminance of each point at the nine intersections of the screen trapezoid, multiplies the area, and then calculates the average of the nine points, which is the ANSI lumen of the projector. The higher the lumen value, the brighter it is. The higher the brightness, the less need to turn off the lights when projecting. ANSI stands for American National Standards Institute.
Question 2: What is lumen?
lumen
Luminous flux unit. The total amount of light emitted by a luminous flux light source is expressed by f ... and its unit is lumen (Lm). For a point light source with luminous intensity of 1 candle, the luminous flux per solid angle (1 sphericity) is "1 lumen".
Lumen is Lumen, so what does Lumen mean? Well, seriously speaking, lumen actually represents the intensity of light, that is, the unit of luminous flux (luminous flux refers to the total amount of light emitted by a light source in a certain unit time, generally called beam). In short, lumen is the amount of light that shines on the surface of an object.
Question 3: What does the lumen of the projector mean? The so-called lumen simply refers to the brightness of a candle at a distance of one meter. . The higher the lumen number of the projector, the higher the brightness of the machine. Generally, the better LCD projectors on the market have a standard lumen number of about 600 ANSI lumens.
2. Brightness and lumens
Brightness is an important technical index of projector. Almost all manufacturers' product manuals have the brightness of xxxxANSI lumens, so many people mistakenly think that lumens are the unit of brightness, which is obviously wrong. This is because brightness refers to the brightness of an object, defined as the luminous intensity per unit area, and its unit is nitt, 1 nitt = 1 Kanter/square meter; Lumen (LM) is the unit of luminous flux, indicating the amount of radiant light energy per unit time.
Generally in 1000-3000 lumens.
Question 4: What is the difference between luminous flux and lumen? Luminous flux refers to the radiant power that human eyes can feel, which is equal to the product of the radiant energy of a certain band and the relative visibility of the band in unit time. Because the relative visibility of human eyes to light with different wavelengths is different, the luminous flux of light with different wavelengths is not equal under the condition of equal radiation power.
The unit of luminous flux is lumen. The luminous flux is usually expressed by φ, and theoretically its unit is equivalent to the electrical unit watt, because vision is still related to light color. Therefore, according to the standard light source and the normal vision measurement unit, "lumen" is adopted, and the symbol is lm.
Illuminance, illuminance for short. The illuminance/illuminance on the surface irradiated by light is defined as the luminous flux irradiated on a unit area. Let the luminous flux on bin dS be dφ, then the illuminance e on this bin is: e = dφ/ds. The unit of illumination is Lü (lux), but it is also lux, 1lx= 1lm/. Illuminance indicates the degree to which the surface of an object is illuminated.
Luminous flux = illuminance * area
Do you understand? There is something wrong with your expression!
Question 5: What does1000 lumens mean? Lumens, a unit of luminous flux. A point light source with luminous intensity of 1 Candeira (cd) emits luminous flux of "1 lumen" in unit solid angle (1 sphericity), which is abbreviated as lm.
Similarly, this quantity is aimed at the light source, which describes the total amount of light emitted by the light source, which is equivalent to the optical power. The greater the luminous flux of the light source, the more light it emits.
Question: What do the brightness and lumens of led lamps mean? Brightness refers to the physical quantity of light (reflection) intensity on the surface of luminous body (reflector). The human eye observes the light source from one direction, and the ratio of the light intensity in this direction to the light source area "seen" by the human eye is defined as the brightness of the light source unit, that is, the luminous intensity on the unit projection area. The unit of brightness is Candeira per square meter (cd/m2). Brightness is how people feel about the intensity of light. This is a subjective quantity. Different from illuminance, the objective corresponding quantity defined by physics is light intensity. These two quantities are often confused in everyday language.
Lumen is a physical unit to describe luminous flux, which is physically interpreted as the total luminous flux generated by a candle (cd, candle, luminous intensity unit, equivalent to the luminous intensity of an ordinary candle) at a solid angle (the angle represented by a spherical cone with a radius of 1 m and the central angle with a middle section of about 65).
Brightness is the luminous flux (lumen) in unit area and unit solid angle of a light source in a certain direction. Is in direct proportion.
Question 7: What does projector lumen mean? A unit of lumen and luminous flux. A point light source with luminous intensity of 1 Candeira (cd) emits luminous flux of "1 lumen" in unit solid angle (1 sphericity), which is abbreviated as lm.
Projectors generally use lumens to express their luminous brightness, and the commonly used lumens of projectors are between 1000-4000 lumens. Home projector generally does not exceed 2500 lumens. Educational and public projectors are generally around 5000 lumens. Digital projectors used in cinemas are generally above 10000 lumens. This product is not a civilian product and has little contact. Common household and commercial projectors include LCD and DLP. There is a trend towards DLP.
Lumens are not intuitive when expressed by data, which can refer to people's subjective feelings. For example:
When using the common gain curtain, when the lumen of the home projector is 1000, you can see the picture less than1000 inch in the dark room at night, but you can't see the picture clearly in the well-lit room.
Question 8: What do you mean by 3000-4000 lumens? 3000-4000 lumens is the projection brightness, and the larger the number, the higher the surface projection brightness.
The so-called lumen is a physical unit to describe luminous flux, which is physically interpreted as the total luminous flux generated by a candle (cd, candle, luminous intensity unit, equivalent to the luminous intensity of a common candle) at a solid angle (a unit sphere with a radius of 1 m corresponds to the angle represented by a spherical cone of a spherical cap of 1 m2, and corresponds to a central angle of about 65). Considering that the solid angle of the whole sphere is 4π, the total luminous flux emitted by 1 candle light is 4π (about 12.57) lumens. The total solid angle of a ball of any size is 4π, so the total luminous flux of candlelight is fixed at 4π, which does not change with the change of distance, so it is wrong to say that the total luminous flux emitted by 1 candlelight is 1 lumen at about 0.28m around it.