According to the beam angle, the light distribution curve can be generally divided into: narrow light distribution (< 20°), light distribution (20°> 40°), wide light distribution (> 40°), and there is no strict definition of the width of each manufacturer. The definitions of medium and narrow are also slightly different. Said a half-day definition and classification. Let's look at the real thing - the light distribution curve of the bracket
T = C0°-180° A = C90°-270° The first picture here is our most common polar coordinate distribution curve. To read it, we must first know that the two curves T and A are from where. There is a note below the graph: T = C0°-180°A = C90°-270° This C represents the angle of the horizontal plane (the solid angle is composed of two angles, horizontal and vertical). 0°-180° constitutes a section, and T is the distribution of light on this section. C0°-180° in the bracket is generally defined as vertical and the direction of the tube. The same reason A is the distribution of light on the C90°-270° section. As shown below:
After knowing the profiles represented by the two curves of T and A, let's continue to see how each curve comes from. The origin of the polar plot (at the center of the concentric circle) is the center of the illuminating surface of the luminaire; each concentric circle represents a light intensity value, and the light intensity is greater on the outer ring; the angle values ​​in the figure are the vertical angles on the cross section. The downward direction is defined as 0° as shown below: Note: There is a cd/1000 lm unit in the figure, which means that this is a light distribution with thousands of lumens as the standard. The actual light intensity needs to be converted to get ( Needless to say how to convert, 50 cd under 1000 lm, 100 cd for 2000 lm!). This is done to facilitate the comparison of light distribution between different lamps.
Fortunately, a map below the polar coordinate light distribution curve is actually an equal illumination curve. It is to use a curve to connect the points with the same illuminance. I believe this picture is easy to understand. Note that the same illumination curve is also used for thousands of lumens. You can look up and down to find the feeling of the light distribution curve.
I hope that I can continue to deepen, talk about the meaning of light distribution, and how to understand the wind sand. How do you understand the light distribution of a light fixture? Can you see what Dongdong comes from? I usually explain it to others: because of reflection The cover changes the illumination direction of the light source. The light distribution can know the illumination range of the light, the illumination direction, estimate the effective installation height, the range (of course, related to the light source), and the approximate illumination in the illumination range, of course, measured by the instrument. Light can also know the efficiency of the luminaire. (It can also be used to find the calculus method, but who will have a lamp and a lamp to calculate the trouble?) The meaning of the light distribution is: 1. Make an IES file for illuminance calculation. Or estimate the illuminance by hand. 2, IES can also be used for optical domain network files, used to simulate the real scene effects of lighting operations. In addition, do you think the difference between domestic and imported lamps lies in the light distribution? Is the domestic lamp not doing well because the light distribution is not good? In addition, the efficiency of the lamps of domestic lamps can generally reach, and how much can the efficiency of imported lamps be achieved? (You can divide the downlight, the light panel, the floodlight , and the hanging light according to the different reflectors)
Today we will look at a light distribution curve. This representation is generally used in floodlighting fixtures. Also give you 2 pictures, the latter one is the iso-illuminance curve.
Look at this graph different from the previous one. In fact, you can see that they only show different ways, and the basic elements are the same. The first is that there are two curves, one solid line is C0°-180°, and the broken line is C90°-270°. The horizontal angle value indicates the vertical angle on the section, and 0 degree is the center of the illuminating surface of the luminaire. The longitudinal value indicates the light intensity. Also pay attention to the upper left corner of cd/1000 lm. It can be seen from the dotted line, that is, the line C90°-270° that the luminaire is asymmetrically light-distributed. How to see? Symmetrical asymmetry is mainly angle only. The angle of the light distribution curve is generally defined as follows: the beam angle of the luminaire is the angle contained in the half intensity value of the peak (maximum) light intensity. The above figure shows that the peak of the dotted line is about 1100cd, half of the peak is about 550cd, the angle on the left should be more than 10 degrees, and the right should be less than 10 degrees, so that the lamp can be judged as asymmetric light distribution. The definition of the angle mentioned here is used by the European standard (also commonly used in China), and the American standard is slightly different. It is defined as the peak (maximum) intensity of the 1/10 intensity value contained in the angle of the lamp beam angle. The illuminance curve is not much to say, very simple, pay attention to the black point in the picture, that is the position of the luminaire. From this table, the symmetry property of the lamp can also be verified, and the apparent light is less forward and more backward.
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