How can we make the desk lamp in use funny? We make the base of the desk lamp into an arc, with hollow grooves in the center of the arc. A weighted iron ball rolls in the groove of the arc base of the desk lamp, and when the iron ball rolls into different positions in the groove, the illumination angle of the desk lamp light also varies. In this way, the behavior of adjusting the illumination angle of the lamp becomes very interesting. On the back of the arc base, several reasonable illumination angles of light source are set up in accordance with the daily use of the people, with the bulges of fixed gears.