Wavelength conversion device

A wavelength conversion device, for a projection system, wherein the projection system comprises a light source device and a dichroic element, the light source device provides an excitation beam, the wavelength conversion device is located on a transmission path of the excitation beam, and the wavelength conversion device comprises:

• a first wavelength conversion portion, wherein the first wavelength conversion portion is configured with at least one wavelength conversion material, and is used for receiving the excitation beam and converting the excitation beam into a first color beam;
• and
• a second wavelength conversion portion, wherein the second wavelength conversion portion comprises a wavelength maintenance zone and a plurality of wavelength conversion structures, the second wavelength conversion portion and the first wavelength conversion portion are alternately switched onto the transmission path of the excitation beam, when the second wavelength conversion portion is switched onto the transmission path of the excitation beam, a portion of the excitation beam is incident on the wavelength maintenance zone and becomes a second color beam, and another portion of the excitation beam is incident on the wavelength conversion structures and converted into a predetermined color beam, a first chromaticity coordinate value of the second color beam in color space is (x, y), a second chromaticity coordinate value of the second color beam, after being combined with the predetermined color beam by the dichroic element, in the color space is (x′, y′), and x′≤x and y′≥y.