Electrophotographic apparatus and electrophotographic photosensitive member

An electrophotographic photosensitive member comprising:

• a photoconductive layer;
• a surface layer on the photoconductive layer;
• and
• N intermediate layers disposed between the photoconductive layer and the surface layer, N being an odd number more than 2,
• wherein the electrophotographic photosensitive member is an object irradiated with an image exposure beam having a central wavelength of λ [μm],
• wherein, where n0 is a refractive index of the photoconductive layer, n1 is a refractive index of a first intermediate layer counting from the photoconductive layer side, ni is a refractive index of an ith intermediate layer counting from the photoconductive layer side, i being an integer equal to or more than 1 and equal to or less than N, nN is a refractive index of an Nth intermediate layer counting from the photoconductive layer side, nN+1 is a refractive index of the surface layer, and di is a thickness [μm] of the ith intermediate layer counting from the photoconductive layer side, the refractive indices n0, n1, ni, nN, and nN+1 satisfy the following expression (1):
• n0>n1> . . . >ni> . . . >nN>nN+1 (1)
• wherein, for each of odd-numbered intermediate layers counting from the photoconductive layer side, ni−1 being the refractive index n0 of the photoconductive layer when i is 1 and ni+1 being the refractive index nN+1 of the surface layer when i is N, the refractive index ni satisfies the following expression (2):
• 
• n
• i
• -
• n
• i
• -
• 1
• ·
• n
• i
• +
• 1
• n
• i
• 
• ≤
• 0.02
• (
• 2
• )
• wherein, for each of the odd-numbered intermediate layers counting from the photoconductive layer side, there exists pi for enabling the refractive index ni and the thickness di [μm], pi being a positive integer, to satisfy the following expression (3):
• 
• 4
• ⁢
• ⁢
• π
• ·
• n
• i
• ·
• d
• i
• λ
• -
• (
• 2
• ·
• p
• i
• -
• 1
• )
• ⁢
• π
• 
• ≤
• π
• 16
• (
• 3
• )
• wherein, among combinations in which two intermediate layers are selected from the odd-numbered layers counting from the photoconductive layer side, there exists at least one combination at which q for enabling the sum of the products (ni·di) of the refractive indices ni and the thicknesses di [μm] of one or more intermediate layers disposed between selected two intermediate layers, q being an integer equal to or more than 0, to satisfy the following expression (4):
• 
• 4
• ⁢
• ⁢
• π
• ·
• ∑
• n
• i
• ·
• d
• i
• λ
• -
• 2
• ⁢
• ⁢
• π
• ·
• q
• 
• <
• π
• 2
• .
• (
• 4
• )

An electrophotographic apparatus comprising:

• an electrophotographic photosensitive member including a photoconductive layer, a surface layer, and N intermediate layers disposed between the photoconductive layer and the surface layer, N being an odd number more than 2;
• and
• an image exposure apparatus for irradiating a surface of the electrophotographic photosensitive member with an image exposure beam having a central wavelength of λ [μm] and forming a latent image on the surface,
• wherein, where n0 is a refractive index of the photoconductive layer, n1 is a refractive index of a first intermediate layer counting from the photoconductive layer side, ni is a refractive index of an ith intermediate layer counting from the photoconductive layer side, i being an integer equal to or more than 1 and equal to or less than N, nN is a refractive index of an Nth intermediate layer counting from the photoconductive layer side, nN+1 is a refractive index of the surface layer, and di is a thickness [μm] of the ith intermediate layer, the refractive indices n0, n1, ni, nN, and nN+1 satisfy the following expression (1):
• n0>n1> . . . >ni> . . . >nN>nN+1 (1)
• wherein, for each of odd-numbered intermediate layers counting from the photoconductive layer side, ni−1 being the refractive index n0 of the photoconductive layer when i is 1 and ni+1 being the refractive index nN+1 of the surface layer when i is N, the refractive index ni satisfies the following expression (2):
• 
• n
• i
• -
• n
• i
• -
• 1
• ⁣
• ·
• n
• i
• +
• 1
• n
• i
• 
• ≤
• 0.02
• .
• (
• 2
• )