Abstract: A paper roll fixing device of a printer is provided. The paper roll fixing device includes a first supporting member and a second supporting member. The first supporting member includes a first supporting protrusion part and plural first auxiliary rollers. The second supporting member includes a second supporting protrusion part and plural second auxiliary rollers. The first supporting protrusion part and the second supporting protrusion part are inserted into two ends of a hollow shaft of a paper roll. Consequently, the paper roll is fixed in the space between the first supporting member and the second supporting member, and supported by the first auxiliary rollers and the second auxiliary rollers. Moreover, especially, the paper roll fixing device is applicable to a variety of paper rolls with different diameters.

Abstract: A printing device includes a casing, an upper cover, plural light sources, and a sensing module. The plural light sources are used for emitting plural light beams. The upper cover is connected with the casing, and rotatable relative the casing. The plural light sources are disposed on the upper cover, and arranged in a row. The sensing module is disposed under the plural light sources, and movable relative to the casing along a specified direction. After the light beams transmitted through a gap of the transfer paper are received by the sensing module, the gap is detected by the sensing module. The plural light beams emitted by the plural light sources can be projected onto any movable position of the sensing module. In other words, it is not necessary to align the sensing module and the plural light beams.

Abstract: A paper roll fixing device of a printer is provided. The paper roll fixing device includes a first supporting member and a second supporting member. The first supporting member includes a first supporting protrusion part and plural first auxiliary rollers. The second supporting member includes a second supporting protrusion part and plural second auxiliary rollers. The first supporting protrusion part and the second supporting protrusion part are inserted into two ends of a hollow shaft of a paper roll. Consequently, the paper roll is fixed in the space between the first supporting member and the second supporting member, and supported by the first auxiliary rollers and the second auxiliary rollers. Moreover, especially, the paper roll fixing device is applicable to a variety of paper rolls with different diameters.

Abstract: A clamshell device includes a cover, a flexible supporting plate, and a base. The cover includes a notch, a friction edge, and a lateral slant surface located at an inner wall of the notch. The supporting plate includes a curvy rim, an elongated groove, and a lateral post. The supporting plate is installed on a base and aligned with the notch. When the cover is rotated at a supporting angle, the friction edge is pressed against the curvy rim of the supporting plate. Consequently, the curvy rim is deformed toward the elongated groove to result in interference, and the supporting plate provides a friction force to allow the cover to be fixed at the supporting angle. At the same time, the interference between the lateral post of the supporting plate and the lateral slant surface can facilitate the cover to be fixed at the supporting angle.