What is the definition of a good spotlight? The main function of spotlight is accent lighting, so the premise of using spotlight is to better highlight the accent lighting of lighting. We can measure the quality of light from four dimensions-spot, luminous angle, color temperature and color rendering index.
0 1. Location
As the shape of the projection plane of spotlight light, spot is the yardstick to judge the light quality of lamps. High-quality facula can improve the visual texture of the object to the greatest extent, and the stereoscopic effect of the object is more prominent, and the extended light supplement is more natural.
The lens focuses the light in front of the light source in a penetrating way, and the conical surface can collect and reflect all the side light. The superposition of these two kinds of light can obtain perfect light utilization, beautiful spot effect and uniform light distribution. At the same time, the reflector works synchronously, the intensity of central light gradually weakens outward, and the halo is natural and comfortable, which is undoubtedly a better spot effect.
However, the light distribution of the spot is uneven, and serious dark spots and dark areas appear. The utilization rate of the "glare" light overflowed from the spotlight cup is low, and there are many shadows at the halo boundary, stiff facula, obvious stray shadows and many virtual shadows, which will lead to visual discomfort and reduce the visibility of objects. The key point is that some light rays are directly output without being reflected by a mirror or lens. Severe glare may cause disgust, discomfort and even blindness.
02. Luminous angle
The luminous angle is also called the power angle. Usually we use half power angle, that is, the angle of 50% luminous intensity as 2&; 1/2。 The lighting angles of spotlights are generally 15, 24, 36. The light emitting angles of diodes, that is, their light scattering angles, are mainly controlled by adding a scattering agent in the diode production process. There are three types: high directivity, standard type and scattering type.
Spotlight belongs to high directivity, and is generally encapsulated by pointed epoxy or metal reflector cavity without scattering agent. Small luminous angle and high directivity. It can be used as a local lighting source, and can also be combined with a light detector to form an automatic detection system.
03. Color temperature
What is the color temperature? Simply put, it contains the unit of measurement of color components in light. Theoretically, color temperature refers to the color of an absolute blackbody heated from absolute zero (-273℃). The spectral component of the light emitted by a blackbody after heating is called the color temperature at this temperature, and the unit of measurement is "K" (Kelvin).
But the color temperature is not good or bad, only suitable or not, depending on the needs of specific places. Usually we divide lights into warm yellow light, warm white light and cold white light according to the color temperature value.
Warm color light is also called warm yellow light, and its color temperature is below 3300K, generally around 2700K K. Warm color light is similar to incandescent lamp and contains more red light, which can give people a warm, healthy and comfortable feeling. Suitable for families, houses, dormitories, hotels and other places, or places with relatively low temperature.
Warm white light, also known as neutral light, has a color temperature between 3300 K and 5300 K. Warm white light is soft and makes people feel happy, comfortable and serene. Suitable for shops, hospitals, offices, restaurants, waiting rooms and other places.
Cold light, also called daylight color, has a color temperature above 5300K, and the light source is close to natural light, which makes people concentrate. Therefore, cold light is suitable for offices, conference rooms, classrooms, studios, design rooms, libraries, exhibition windows and other places.
04. Color rendering index
Color rendering index is a parameter common to all light sources, and it is the ability to restore color. Sunlight color rendering index 100, incandescent lamp 100, energy-saving lamp 80-90, led 70-99. The lower the color rendering index, the more distorted the color is to the naked eye.
Under the condition of color adaptation with reasonable tolerance, the consistency between the psychophysical color of CIE test color sample irradiated by the measured light source and the psychophysical color of the same color sample irradiated by the reference light source is measured. The symbol is Ri. The average value of CIE 1974 special color rendering index of eight color samples is generally called color rendering index. The symbol is Ra. Saturated colors with color rendering index Ra > 90 and R9 & gt60 are selected, and the color rendering performance is excellent.
Next, what kind of spotlights are durable? The core of durable spotlights is to prolong the life of lamps, which mainly depends on three points: lamp beads, driving and heat dissipation of lamps.
0 1. lamp bead
A lamp bead is like the brain of a lamp. Some well-known lamp bead brands, such as OSRAM and Corey, have guaranteed quality. Osram chip uses new conversion technology to produce ultra-thin conversion layer, which can withstand higher junction temperature and longer heat dissipation time. As the LED continuously generates heat in the working process, if the heat cannot be dissipated quickly, the LED lamp beads will rapidly decay at high temperature, and the service life will be greatly shortened.
02. Drive
Constant-current driving is widely used in the current power supply research and design field, because constant-current mode can prevent the driving current from exceeding the maximum rating, thus ensuring that LED lamps meet the expected brightness and color temperature requirements, and stable constant-current input and output can more effectively extend the service life of lamps.
Especially when dimming lamps is needed, it is difficult to maintain the consistency of illumination brightness. A small increase in voltage will lead to an exponential increase in current, and if it is not adjusted properly, it will sometimes damage LED lights. In addition, the constant current circuit is not easy to be biased by the heat generated inside or outside the element itself, which reduces the forward resistance (voltage difference), increases the current passing through the element and improves the long-term reliability of the LED lamp.
03. Heat dissipation of lamps and lanterns
The heat dissipation of lamps will directly affect the service life of lamp beads. Hot air flow and air convection form a high-speed cycle to ensure the most stable working state of lamps.
The heat source of LED lighting mainly comes from light source and power supply. For the heating of light source, it is usually necessary to pay attention to the effective contact area between the PCB board of light source and the joint surface of radiator. The larger the effective contact area, the better the heat dissipation. In addition, we should also pay attention to whether the heat conduction interface between different media is smooth. The joints between heat conductors should be tight enough, and the gap between the contact surfaces of embedded parts should be as small as possible.
The natural convection heat dissipation mode of LED lamps also needs effective heat dissipation area, so generally speaking, the effective heat exchange area can be increased by properly roughening the outer wall of the radiator. In addition, when spraying different colors, the spraying thickness, thermal conductivity and thermal radiation performance of such coatings should also be considered.
Having said that, do you know how to choose a good and durable spotlight? To put it simply, the key for a good spotlight to fully highlight accent lighting is to look at four elements: luminous angle, spot, color temperature and color rendering index. The control of the three standards of lamp bead, drive and heat dissipation can prolong the life of spotlight, which can be called durable spotlight.