Cap opening and closing apparatus and method of controlling same

A cap opening and closing apparatus for opening and closing a cap of a microtube including a container body and the cap connected to the container body via a hinge portion, comprising:

• a first arm that rotates about a first rotation axis, the first arm including a catch portion that moves, engages with an edge portion of the cap of the microtube placed at a predetermined position, and opens the cap as the first arm rotates in a first direction;
• a second arm that rotates about a second rotation axis, the second arm including a pressing member that presses and closes the cap of the microtube placed at the predetermined position as the second arm rotates in a second direction opposite to the first direction;
• a control unit that opens the cap by rotating the first arm and the second arm in the first direction with the cap positioned between the catch portion and the pressing members and during the opening rotation, a specific rotational position relationship is maintained in which an angle formed by a first straight line joining the first rotation axis and the catch portion and a second straight line joining the second rotation axis and the pressing member is within a predetermined angle range;
• a pin that can slide to transition between a pressed state in which a side surface of the microtube placed at the predetermined position is pressed by a first end portion of the pin and a non-pressed state in which the side surface is not pressed;
• and
• a biasing member that rotates together with rotation of the second arm in the second direction and slides, according to the rotation, the pin to transition the pin into the pressed state:
• wherein the biasing member includes an inclined surface.