Lighting Lighting Terms

Efficacy: The ratio of the total luminous flux emitted by a light source to the electric power (watts) consumed by the light source is called the luminous efficacy of the light source. The unit is: Lumens/Watt (lm/w). Lumens are Lumens:.

Lumens: The sum of the light emitted by a light source in a unit of time is called the luminous flux of the light source. Symbol: Φ, unit lumen Lm. For example, the luminous flux of a 40W ordinary white-knit lamp is 350---470lm, and the luminous flux of a 40W ordinary straight-tube fluorescent lamp is about 2800lm, which is 6-light for white knit lamps. -8 times.

Color Temperature: When the color of light emitted by a light source is the same as the color of light emitted by a black body at a certain temperature, the temperature of the black body is called the color temperature of the light source. Because most of the light emitted by the light source is commonly known as white light, the color table temperature or correlated color temperature of the light source is used to refer to the degree of its light color relative to white to quantify the light color performance of the light source. According to Max Planck's theory, heating a standard blackbody with complete absorption and radioactivity, the temperature gradually increases as the luminosity increases; the black body locus on the CIE chromatic coordinates shows the blackbody from red-orange-yellow - Yellow white - white - blue and white process. The temperature when the black body is warmed to the same or close to the light color as the light source is defined as the correlated color temperature of the light source, and the color temperature is expressed in absolute K (Kelvin, or Kelvin). (K=°C+273.15) . Therefore, when the blackbody is heated to red, the temperature is about 527 degrees Celsius or 800K, and other temperatures affect light color changes. The more bluish light color, the higher the color temperature; the lower the color temperature, the more reddish it is. The light color of the day changes with time: 40 minutes after sunrise, the light color is yellow, the color temperature is 3,000K, the snow is white at noon, it rises to 4,800-5,800K, and it is about 6,500K at noon on cloudy days; Reddish, the color temperature dropped to 2,200K. The relative color temperature of other light sources. Since the correlative color temperature is in fact a black body radiation close to the light source light color, the evaluation value of the light source light color performance is not an accurate color contrast, so the two light sources with the same color temperature value may still have a light color appearance. There are some differences. Only Feng Shuangwen can not understand the color rendering ability of the light source on the object, or how the object color is reproduced under the light source. Light source color temperature is different, light color is also different, color temperature below 3300K has a stable atmosphere, warm feeling; color temperature in the 3000 - 5000K as the middle color temperature, there is a refreshing feeling; color temperature above 5000K has a cold feeling.

Colour rendering index: The continuous spectrum of the radiation of sunlight and incandescent lamps, in the range of visible light wavelengths (380nm-760nm), containing various shades of red, orange, yellow, green, cyan, blue and violet. . The object displays its true color under sunlight and incandescent light, but when the object is exposed to a non-continuous spectrum gas discharge lamp, the color will have different degrees of distortion. We refer to the degree of presentation of the true color of the light source to the color rendering of the light source. In order to quantitatively evaluate the color rendering of the light source, we introduce the concept of color rendering index, which is based on the standard light source, and its color rendering index is set at 100. The color rendering index of the rest of the light sources is less than 100. The color rendering index is represented by Ra. The larger the Ra value, the better the color rendering of the light source.

Ballast: A ballast is a control device used by a gas discharge lamp for starting and current limiting. Due to the negative volt-ampere characteristics of a gas discharge lamp, a ballast is required to initiate lamp discharge and to limit lamp inertia. The ionization of the gas increases the vapor pressure of the mercury, and the ultraviolet rays generated after the electron bombardment of the mercury vapor discharge excite the fluorescent lamp and emits light. After the startup is completed, the ballast functions as a current limiter, so that the lamp starts to work normally. The commonly used ballast is Electric device. Inductance ballast is a high-inductance and high-resistance device. It has been working in series with the lamp. It not only consumes active power, but also consumes reactive power, and the power factor is also very low. As a result, the efficiency of lighting is reduced. . Compared with ordinary ballasts, electronic ballasts have the advantages of low power consumption, high power factor, fast ignition speed, and no noise interference. The energy saving rate is as high as 75%, and the power factor can be increased from about 0.5 to above 0.9. At the same time, the high-frequency power supply from 50Hz to 25kHz to 40kHz, with minimal stroboscopic effect, is conducive to vision protection and production safety, greatly reducing visual fatigue and reducing personal injury opportunities.

Glare index: Glare is a glare effect caused by an inconsequential light distribution or a large change in brightness. It is classified into glare and reflected glare. Direct glare refers to the light emitted by the light source directly into the human eye; reflective glare refers to the reflection of light on the shiny wall surfaces, tables, mirrors and other objects into the human eye. Intense glare can make the interior light incongruous, making people feel uncomfortable, and in severe cases it can feel dizzy and even blind.

Lumen maintenance: The light output of a lamp is gradually attenuated as operating time increases, at a fixed time the lamp's luminous flux relative to the percentage of the initial luminous flux at which the lamp ignites 100 hours. This is known as the lumen maintenance rate for this fixed time. National standard requirements: 2000h not less than 78%. Foreign advanced level: 2000h is not less than 90%. US Energy Star: 40% of rated life is not less than 80%. Domestic level: Focus on the quality of the company, and the use of protective film technology, can basically reach the national standard.

Brightness: The intensity of light reflected from an object in a certain direction, that is, the intensity of light reflected by a unit area in a certain direction. Symbol L, unit cd/m2. Illuminance indicates the amount of incident light per unit area. Brightness is the intensity of the reflected light of an object seen from a certain direction by the eye.

Footcandle: The footcandle is used to measure the amount of light per square foot projected on an object.

Spectrum: The distribution of light in the order of wavelength is called the spectrum. Each light source can display its spectral energy distribution on the spectrum diagram according to its wavelength composition. The spectral energy distribution of sunlight and incandescent bulbs is a continuous curve, while the general discharge lamp is a discontinuous curve.

Incandescence lamp: Incandescent lamp is the earliest mature artificial electric light source. It uses the principle of filament heating and light emission. In general, incandescent bulbs have lower luminous efficiency and shorter lifespan, but are more convenient to use.

Fluorescent lamps: One of the commonly used light sources of the T5 T8 T10 T12, which has many advantages over other light sources.

Gas discharge lamp (HID = high intensity discharge): The light emission principle of this type of light source is that the gas between the two electrodes is excited by electrons and emits light. They can be divided into low-pressure gas discharge lamps such as fluorescent lamps and high-pressure gas discharge lamps such as mercury lamps, high pressure sodium lamps, and metal halide lamps.

Light-emitting diode (LED): The light-emitting diode is a pn diode made of a special material. Under forward bias, when the electrons flow at the junction, they emit light during the recombination and extinction. The small size and low luminous efficiency are not high, but they have developed rapidly in recent years. The applicable occasions have been extended to signal lamps, indicator lamps, and even lighting applications for special occasions.

Invisible light: Electromagnetic radiation with a wavelength of 360 to 830 nm is called invisible light with respect to visible light. Electromagnetic waves with a wavelength of less than 360 nm are most commonly known as ultraviolet rays. Others include x-rays, r-rays, and cosmic rays. Electromagnetic radiation greater than 780 nm includes infrared rays and radio waves. Surface-Mount LED Three-color RGB (red, green, blue) Monochrome of three different colors, mixed in different proportions, can combine most of nature's colors.

Accent lighting: A directional lighting used to emphasize a particular target or to attract attention to a part of the field of view.

Accommodation: The process of changing the focus of a person's eyes from one point to another. Adaptation refers to a process in which the human visual system adapts more or less, or different shades of light, which can affect visual acuity.

Ambient lighting: All-area lighting that produces full lighting.

Average luminance, of a surface: The total luminous flux per unit area of ​​the light surface that actually exits.

Average luminance, of a luminaire: refers to the luminosity at a given angle divided by the projected area of ​​the luminaire in that direction.

Baffle: An opaque or translucent object that shields light from direct sunlight at a certain angle or absorbs unwanted light.

Beam angle: refers to the angle between two directions of 50% of maximum luminosity on a plane perpendicular to the centerline of the beam.

The power distribution curve (candle power distribution curve): refers to the curve of the change of the photometric degree of a light or the center of the light source of the lamp in a polar coordinate system on a plane.

Roof clear window (clere story): The lighting design of a building with a transparent roof or a wall with a lighting glass window.