Vehicle lamp unit and rotary light shielding member

A vehicle lamp unit comprising:

• an optical system configured to form a light distribution pattern ahead of a vehicle;
• and
• a rotary light shielding member rotatable around a rotational axis thereof, and including a light shielding portion having a side surface continuously formed by a plurality of spiral surfaces where a plurality of edge portions are formed, and configured to block at least a part of light emitted from a light source,
• wherein the plurality of spiral surfaces of the light shielding portion are formed to approach toward a left end of the rotary light shielding member, respectively, while rotating the rotary light shielding member toward a rear side of the vehicle around the rotational axis thereof when viewed in a front side of the vehicle, such that a blocked quantity of light emitted from the light source by the rotary light shielding member is changed,
• the light shielding portion is configured to form a plurality of light distribution patterns including an inclined cutoff line extending in a direction that crosses a horizontal line, and a horizontal cutoff line connected to the inclined cutoff line, respectively such that a position of the inclined cutoff line moves along the horizontal line, while rotating the rotary light shielding member around the rotational axis, and
• the light shielding portion is configured such that a change of a position of each of the plurality of edge portions of the side surface that is projected as the inclined cutoff line in a direction of the rotational axis of the rotary light shielding member becomes nonlinear in relation to a change of a rotational position of the rotary light shielding member while rotating the rotary light shielding member around the rotational axis thereof.