Protective case for tablet computer and two-in-one computer

A two-in-one computer, comprising:

• a tablet computer;
• a keyboard;
• and
• a protective case comprising:
• a first support plate;
• a second support plate, wherein the first support plate is hinged to the second support plate using a damping rotating shaft comprising a shaft sleeve and a shaft core, wherein an elastic notch is opened on a side wall of the shaft sleeve, wherein the elastic notch communicates with a shaft hole in the shaft sleeve, and wherein the elastic notch extends through two end;
• and
• a cover plate,
• wherein the first support plate, the second support plate, and the cover plate are located in a same horizontal plane and are sequentially arranged in a first direction, wherein the second support plate is rotatably connected to the cover plate,
• wherein a bottom support is disposed on an edge of one end that is proximate to the cover plate and that is on an upper surface of the second support plate,
• wherein the cover plate is configured to protect a front surface of the tablet computer after rotating and overlapping the first support plate and the second support plate,
• wherein a rear surface of the tablet computer is supported on the first support plate and the second support plate of the protective case,
• wherein a side wall of the tablet computer is detachably connected to the bottom support of the protective case,
• wherein the keyboard is installed on the cover plate of the protective case,
• wherein one of the shaft sleeve or the shaft core is secured to the first support plate, wherein the other one of the shaft sleeve or the shaft core is secured to the second support plate, wherein the shaft sleeve is made of an elastic material, wherein a base circle arc section and two changeable-diameter arc section are formed around an inner wall of the shaft sleeve, wherein the two changeable-diameter arc sections are symmetrically disposed using a central axis of the shaft sleeve as a symmetry axis, wherein two flat positions are formed on the outer circular surface of the shaft core, wherein the two flat positions are in a one-to-one correspondence with the two changeable-diameter arc sections, wherein the shaft core is cooperatively sleeved in the base circle arc section, wherein a radius of the changeable-diameter arc section is less than a radius of the base circle arc section, and wherein a flat position is formed at a position that is on an outer circular surface of the shaft core and that fits the changeable-diameter arc sections.