We use the VBR-300 light meter to evaluate the color temperature in terms of illuminance and color temperature.
A-level desk lamp, with the lamp as the center, the small circle of 30cm should reach 300lx, and the outer ring of 50cm should reach 150lx. For a better AA-level table lamp, the small circle of 30cm should reach 500lx, and the outer ring of 250cm should reach 150lx.
Place the lamp on the horizontal table in the normal position, the light source is 40cm away from the horizontal table, and the vertical projection point of the geometric center of the light outlet is the center of the circle, draw two semi-circles with a center angle of 180° with a radius of 30cm and 50cm from the center of the circle respectively, and then measure them respectively. The LUX of eleven points O, A, B, C, D, E, F, G, H, I, J. It is relatively easy to make the illumination at point O high, but any comfortable light source must be as uniform as possible. If the center and surrounding light and shade change too much, the eyes need to adjust the pupil frequently to adapt to the different brightness. Eyes get tired easily. There are requirements for the uniformity of the desk lamp, the difference between the center and the inner ring cannot exceed 3 times, and the inner ring and the outer ring cannot exceed 3 times, that is, the illumination uniformity in the 120°fan-shaped area of ≤300mm is ≤ 3. Illumination uniformity in the 120° fan-shaped area of ≤500mm should be ≤3. The table lamp in the picture: O point (center), 888lx, B+C+D points of 120°fan-shaped are ≤300mm are 400lx, 304lx, 344lx respectively. The value of the center point divided by the lx of these three points is all less than 3. For the 120°fan-shaped area of ≤500mm, the G+H+I points are 104, 80, and 88 respectively, it is more than 3 times worse than the three points B, C, and D, indicating that illumination uniformity in the fan-shaped area is not good at 120°of ≥300mm and ≤500mm. Moreover, the lux of G, H, and I points don’t meet the requirements of A-level desk lamps.
This desk lamp meets the requirement.