A hand-held graphical calculator having a display and an input area is described. An lower end surface in the axial direction of the magnet is fixed or secured to the same plane as a lower end surface in the axial direction of the yoke, or the lower end surface in the axial direction of the magnet is fixed or secured so as to protrude a little from the lower end surface in the axial direction of the yoke. A plurality of light emitting modules are disposed in the plurality of first cavities. An RF gap area located within the cavity is totally segregated from the gaps between the interdigitated metal electrodes. A lock ring groove is formed in one of the first plate, the second plate, and between the first plate and the second plate.