Phosphor unit, light source device, and projector

A phosphor unit comprising:

• a phosphor wheel configured to rotate around a rotation axis;
• a peripheral wall surrounding the phosphor wheel along a circumferential direction around the rotation axis;
• a heat receiving plate intersecting the rotation axis on the rotation axis, facing the phosphor wheel, and spaced apart from the phosphor wheel;
• and
• a heat receiving fin fixed to the heat receiving plate and surrounded by the peripheral wall, wherein
• the phosphor wheel includes
• a substrate having a first surface and a second surface that is provided on an opposite side from the first surface and faces the heat receiving plate, and configured to rotate around the rotation axis,
• a wavelength conversion portion disposed on the first surface and containing a phosphor that converts a wavelength of incident light, and
• a heat dissipating fin disposed on the second surface, and including a plurality of first fins that generate an airflow in a direction from a center of the second surface toward outside by rotation of the substrate and dissipate heat transferred from the wavelength conversion portion to the generated airflow, and
• the heat receiving fin includes a plurality of second fins through which an airflow circulating from the phosphor wheel to the phosphor wheel via the peripheral wall and the heat receiving plate flows, and that receives heat from the flowing airflow and transfers the heat to the heat receiving plate,
• wherein
• the plurality of second fins include a plurality of peripheral wall side fins,
• the plurality of peripheral wall side fins are disposed between the phosphor wheel and the peripheral wall in a direction orthogonal to the rotation axis, and
• wherein the plurality of peripheral wall side fins and the heat dissipating fin of the phosphor wheel are disposed to overlap each other in a direction orthogonal to the rotation axis.