Complex triangular relationship in LED lighting

Usually hear the question of Party A or the designer: how much is the beam angle of the lamp? There are wood? Then the manufacturer's sales staff in accordance with the data to indicate that this is how many degrees angle. Like a lamp can be lit, all dumbfounded wood with ah? Geometry who will! How can this lamp is 12 degrees, how to see also have 30 degrees ah. Party A and the designer has expressed dissatisfaction with the clerk shook his head, become dejected and despondent rendered speechless. Such scenes have wood?

Or someone asked: how much is this light cut angle? Cut off angle ah, you do not know there are wood? You are not easy to answer up, a look at the glare is very powerful ah, how could it be 60 degrees cut angle? Can't you answer the question? There are wood? Well, today, we have a look at the relationship between you and the customer has always been a problem you have a headache triangle.

Beam angle

A picture is worth a thousand words. The beam angle (Beam angle) is the angle between the two directions of the light intensity at the plane of the center line of the vertical beam, which is equal to the maximum intensity of 50%. This parameter is used to measure the light intensity distribution of the narrow angle reflection type light source, lamp and lamp. Explanation: the beam angle does not refer to the whole beam inclusive angle, so break out of the spot may not be from the angle between the center to the outer edge of the spot lamp from the lamp to the spot center line and connect the center point of the.

Advanced: it is not used to test the illuminance, get the point of 50% illuminance is the point of 50% light intensity? The answer is: NO! According to the cosine law and the inverse square law, the ideal state, 50% light intensity of the point of illumination value Ep should be:

In addition: outdoor lamps often 1/10 peak light intensity of the angle of the light beam.

Two, shading angle (protection angle shielding angle)

A picture is worth a thousand words. Shielding (angle) refers to the angle between the edge of the light source and the edge of the opening of the lamp and the angle between the horizontal line.

Three, cut off angle

Note: the lamp light interception angle (cut-off angle) is often confused with the shading angle, but a difference, it is in fact the shading angle. Lazy on the map, but it is not nonsense, look at the above chart to understand. The angle of light and the angle of light interception are commonly used to control the glare of the lamp. The outdoor street lamp is directly used to measure the glare level of the luminaire.

Explanation: protection angle of 30 degrees (light interception angle of 60 degrees) of the lamp, why stand in the line of sight of 30 degrees of geometric position, still so dazzling? Above.

As can be seen from the picture, the light of the lamp, in addition to the direct light source may cause glare, the light of the surface of the material can also cause glare. In addition, the overall brightness of the lamp surface may also cause indoor materials, especially the surface of the computer, such as reflective glare.

In general, the control of light environment glare is a systematic project. It is not enough to look at the protective angle, and now many lighting designers use only the beam angle to measure the glare control of the lamp, it is a bit simple and rough. Conditional, or should look at the light distribution curve.