Light conversion structure, backlight module, color filter substrate and display device

A light conversion structure, comprising:

• a light filter structure comprising a first optical film layer and a second optical film layer which are alternately arranged and attached to each other, a total number of the first optical film layer and the second optical film layer being N, wherein
• N is an even number, and a refractive index of the first optical film layer is greater than that of the second optical film layer, one of a surface of the first optical film layer far away from the second optical film layer and a surface of the second optical film layer far away from the first optical film layer is a light incident surface of the light filter structure, and the other one of the surface of the first optical film layer far away from the second optical film layer and the surface of the second optical film layer far away from the first optical film layer is a light-exiting surface of the light filter structure, wherein
• a part of an incident light of first color that is reflected by the light incident surface is a first reflected light, a part of the incident light of first color that is reflected by an interface between the first optical film layer and the second optical film layer is a second reflected light, and an optical path difference between the first reflected light and the second reflected light is an integer multiple of a wavelength of the incident light of first color,
• the light filter structure comprises one pair of first optical film layer and second optical film layer, the first optical film layer has a refractive index of n1 and a thickness of d1, and the second optical film layer has a refractive index of n2 and a thickness of d2, the incident light of first color has a wavelength of λ,
• when the light incident surface is the surface of the second optical film layer far away from the first optical film layer, the incident light of first color satisfies the following formulas upon being incident into the light filter structure:
• 2n2d2=2k*(λ/2), k=1,2,3 . . . ;
• 2n2d2+2n1d1−(λ/2)=2k′*(λ/2), k′=1,2,3 . . . ;
• 4n2d2=2k″*(λ/2), k″=1,2,3 . . . ,
• when the light incident surface is the surface of the first optical film layer far away from the second optical film layer, the incident light of first color satisfies the following formulas upon being incident into the light filter structure:
• 2n1d1−(λ/2)=2k*(λ/2), k=1,2,3 . . . ;
• 2n1d1+2n2d2=2k′*(λ/2), k′=1,2,3 . . . ;
• 4n1d1−3(λ/2)=2k″*(λ/2), k″=1,2,3 . . . .