Reflective diffusion device and projection device

A projection device, comprising:

• a lighting module, a light valve, and a projection lens, wherein the lighting module is configured to provide a lighting beam, the light valve is disposed on a path of the lighting beam to convert the lighting beam into an image beam, the projection lens is disposed on a path of the image beam and is used to project the image beam out of the projection device;
• wherein the lighting module comprises:
• a light source module, configured to emit an excitation light beam;
• a reflective diffusion device, comprising a reflecting member, a diffusing member, and a driving element;
• wherein
• the reflecting member has a central axis and comprises a reflective surface facing the light source module, wherein an included angle greater than 0 degrees and less than 90 degrees is between the reflective surface and the central axis;
• the diffusing member is disposed on at least a portion of the reflective surface of the reflecting member, wherein the excitation light beam is incident on a first position of the reflective diffusion device in an incident direction parallel to the central axis, is reflected by the reflective surface of the reflecting member, is transmitted and incident on a second position of the reflective diffusion device, and is then reflected by the reflective surface to maintain the excitation light beam or form a diffused light beam, the excitation light beam or the diffused light beam exits from the reflective diffusion device in an exit direction parallel to the central axis, and the first position and the second position are symmetrical to the central axis;
• and
• the driving element has a rotating shaft, the reflecting member is disposed on the rotating shaft of the driving element, the rotating shaft is collinear with the central axis, and the driving element is configured to drive the diffusing member and the reflecting member to rotate around the central axis;
• and
• a wavelength conversion device, disposed on a path of the excitation light beam or the diffused light beam from the reflective diffusion device to convert the excitation light beam or the diffused light beam into a converted light beam, wherein the converted light beam transmitted out of the lighting module serves as the lighting beam provided by the lighting module,
• wherein the reflective surface is ring-shaped around the central axis, the diffusing member is disposed on the portion of the reflective surface of the reflecting member to form at least one diffusion section, and an exposed portion of the reflective surface that is not covered by the diffusing member forms at least one reflection section, and a sum of an angle distributed by the at least one diffusion section with the central axis as a center of a circle and an angle distributed by the at least one reflection section with the center axis as the center of the circle is 360 degrees.