A paper dispenser includes a reel tube having a lateral opening and a cavity, a central shaft disposed inside the cavity, a set of spring for shaft with one end inserted and fixed on the central shaft while the other end is connected with the beginning end of the reel. The drive motor is connected to a work tool mounted at one end of the guide tube via a drive shaft mounted in the guide tube. When a client requests a custom video image, the computing device obtains a second video image by merging images of all conference participants for the client, and sends to the client. The engaging member and the engaged member are constituted to engage with each other in an upper-and-lower direction such that a relative position thereof varies according to a change of positional deviation between the first guide rail and the second guide rail. By this, the image of the measurement object can be captured during the time when the X-ray fluorescence image is standing still, so sensitivity can be secured while increasing the resolution.