WAVEFORM CONVERSION ELEMENT, LIGHT SOURCE DEVICE, VEHICLE HEADLIGHT, DISPLAY DEVICE, LIGHT SOURCE MODULE, AND PROJECTION DEVICE

To realize a wavelength conversion element with which a temperature rise of a fluorescent layer is controlled and fluorescence emission intensity is improved.SOLUTION: Provided is a wavelength conversion element (30a, 30b, 40a, 50a, 60a, 70a, 81, 81a, 81b, 81c, 81d) including a phosphor layer in which phosphor particles (34a, 34b, 36a, 36b) are dispersed in binders (33, 35), the phosphor layer having a first region (31, 41, 51, 61) and a second region (32, 42, 52, 62), the temperature of the first region being higher than that of the second region due to the influence of excitation light (14). The phosphor particles are composed of phosphors the luminescent center element of which is doped, and are constituted so that at least two of the concentration of the luminescent center element, the size of phosphor particles and the volume ratio of phosphor particles to the binder change over the first to the second regions of the phosphor layer.SELECTED DRAWING: Figure 3 【課題】蛍光層の温度上昇を制御し、蛍光発光強度が向上した波長変換素子を実現する。【解決手段】波長変換素子（３０ａ、３０ｂ、４０ａ、５０ａ、６０ａ、７０ａ、８１、８１ａ、８１ｂ、８１ｃ、８１ｄ）は、バインダ（３３、３５）中に蛍光体粒子（３４ａ，３４ｂ、３６ａ，３６ｂ）が分散した蛍光層を備え、蛍光層は、第１の領域（３１、４１、５１、６１）と第２の領域（３２、４２、５２、６２）とを有し、励起光（１４）の影響により第２の領域より第１の領域が高温となる波長変換素子であって、蛍光体粒子は、発光中心元素がドープされた蛍光体から構成され、蛍光層の第１の領域から第２の領域にわたって発光中心元素の濃度、蛍光体粒子の大きさ、および、バインダに対する蛍光体粒子の体積比率の少なくとも２つが変化するように構成される構成である。【選択図】図３