There are four main types of light source: incandescent lamp, halogen tungsten light, fluorescent lamp and LED. Three types of light sources have advantages and disadvantages, different people may like different light color and brightness, should be due to people. In order to be able to project most of the light onto the desktop, the location of the light source for the writing desk lamp is usually horizontal or downward.
In the purchase of writing desk lamps, in addition to the optical performance inspection, but also check whether other performance is qualified.
One pull, two tune, three shakes, four touches. "Pull" means to pull the power cord plug out of the socket, force the power cord to the light outside, to see if the wiring is solid. The power cord cannot be detached from the lamp chamber. "Adjust" refers to adjust the table lamp various work position, adjust, can not make the sound, after adjusting the work position should be able to conveniently and reliably lock tightly. "Shake" refers to the table lamp to the most unfavorable work position, and then gently shaking the table lamp placement of the plane, to see if the lamp is easy to overturn, the lamp smoothness is not good, easily overturned. "Touch" refers to the lamp lit for a period of time (2 hours), touch the lamp with the hand when the hot parts are easy to touch the heat, in case of future use was accidentally scalded.