Abstract: The present disclosure relates to an electric toothbrush, including a shell, a toothbrush head, a first spiral bevel gear, a second spiral bevel gear, and a drive motor. The toothbrush head is connected with the second spiral bevel gear; the first spiral bevel gear and the second spiral bevel gear are in transmission connection; the first spiral bevel gear is arranged above the drive motor and is in transmission connection with the drive motor; a central axis of the first spiral bevel gear is perpendicular to a central axis of the second spiral bevel gear; and the drive motor has a stepped shaft connected to the first spiral bevel gear. The first spiral bevel gear and the second spiral bevel gear are used to drive the toothbrush head to rotate, so that the drive is steady and the transmission efficiency is high. A main shaft of the drive motor adopts the stepped shaft, which can improve the transmission efficiency, so that the transmission is steadier.

Abstract: The present invention relates to a spectrally selective emitter and a design method thereof. The designed emitter has a one-dimensional layered structure, including a first layer, a second layer and a third layer arranged in sequence, wherein both the first and third layers are hafnium oxide layers, and the second layer is a hafnium oxide layer with multiple erbium oxide nanoparticles distributed. The designed emitter is a material-type emitter with spectrally selective emittance. Compared with the traditional structure-type emitter, the material-type emitter has high thermal stability and oxidation resistance, which can fundamentally solve the high-temperature degradation problem.