Actuator and backrest device, and piece of seating furniture having one such

An actuator device for the guided linear and in particular quasi-vertical movement of a first element relative to a second element over a predefined displacement path, comprising:

• a guide housing;
• a displacement profile that is situated in the guide housing and has a longitudinal axis;
• and
• a locking element,
• wherein
• the displacement profile or the guide housing includes a latching row that extends along the longitudinal axis and has a plurality of latching ramps,
• the locking element is resiliently supported, and in a latching position engages with the latching row so that the displacement profile is movable in a stepwise manner in a first direction along the longitudinal axis with respect to the guide housing, and a movement in a second direction, opposite the first direction, is blocked by the locking element striking against one of the latching ramps,
• the locking element is held, in a release position, in a disengaged state from the latching row, so that the displacement profile is freely movable in the first direction and in the second direction along the longitudinal axis with respect to the guide housing,
• the locking element is supported so that it is rotatable about a rotational axis,
• the locking element in the latching position is resiliently rotated about the rotational axis into the latching row, and preferably rotates back and forth about the rotational axis when the displacement profile moves in the first direction along the longitudinal axis with respect to the guide housing, and
• the locking element in the release position is held, while being rotated about the rotational axis into a retaining position, until it is disengaged from the latching row.