# US 8,771,908 B2 · Electrophotographic apparatus and electrophotographic photosensitive member

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- Number: US 8,771,908 B2
- Document ID: US8771908B2
- Status: Granted
- Kind: B2
- Application number: 13/107,425
- Filed: 2011-05-13
- Published: 2011-11-24
- Granted: 2014-07-08
- Earliest claimed: 2010-05-18
- Assignees: Canon Kabushiki Kaisha
- Applicants: Yukihiro Abe
- Inventors: Yukihiro Abe
- Web page: https://patentgrep.com/patent/US8771908B2

## CPC

- G03G 15/75: {Details relating to xerographic drum, band or plate, e.g. replacing, testing (electrographic recording members per se G03G5/00)}
- G03G 5/047: characterised by the charge-generation layers or charge transport layers {(G03G5/0433 and G03G5/0436 take precedence)}
- G03G 5/14: Inert intermediate or cover layers for charge-receiving layers (for photoconductive, charge-generation or charge-transporting layers G03G5/04)
- G03G 2215/00957: Compositions
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An electrophotographic apparatus and an electrophotographic photosensitive member for use in the electrophotographic apparatus are provided. The number of intermediate layers between a photoconductive layer and a surface layer is an odd number more than 2, and the refractive index monotonically decreases from the photoconductive layer toward the surface layer. The refractive index of an odd-numbered intermediate layer is in a predetermined range of the geometrical mean of the refractive indices of the two layers adjacent to the odd-numbered intermediate layer, and the product of the refractive index and the thickness is in a specific range of an odd multiple of λ/4n. The sum of the products of the refractive indices and the thicknesses of one or more intermediate layers disposed between at least two odd-numbered intermediate layers is in a range of −π/2<θ<π/2 in the terms of phases.

## Claims

### Claim 1

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
)
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
)

### Claim 2 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein pi is 1 or 2.

### Claim 3 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein N is an odd number more than 4.

### Claim 4 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein, for one or more even-numbered layers counting from the photoconductive layer side, there exists qi for enabling the refractive index ni and the thickness di [μm], qi being an integer equal to or more than 0, to satisfy the following expression (5):

4
⁢
⁢
π
·
n
i
·
d
i
λ
-
2
⁢
⁢
π
·
q
i

≤
π
8
.
(
5
)

### Claim 5 (depends on 4)

The electrophotographic apparatus according to claim 4, wherein qi is 1, 2, 3, or 4.

### Claim 6 (depends on 4)

The electrophotographic apparatus according to claim 4, wherein N is an odd number more than 4, and
wherein, for one or more even-numbered intermediate layers counting from the photoconductive layer side, there exists qi for enabling the refractive index ni and the thickness di [μm], qi being an integer equal to or more than 0, to satisfy the above expression (5), and
for the remaining one or more even-numbered intermediate layers, there exists pi for enabling the refractive index ni and the thickness di [μm], pi being a positive integer, to satisfy the above expression (3).

### Claim 7 (depends on 4)

The electrophotographic apparatus according to claim 4, wherein N is an integer that satisfies the following expression (6):
N=4·k−1 (6)
where k is a positive integer, and
wherein, among combinations in which two even-numbered intermediate layers arranged substantially symmetrical with respect to a (2·k)th intermediate layer counting from the photoconductive layer side, there exists at least one combination at which the refractive index ni and the thickness di [μm] of each of selected even-numbered intermediate layers satisfy the above expression (5).

### Claim 8 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein N is an integer that satisfies the following expression (7):
N=4·h+1 (7)
where h is a positive integer, and
wherein, for each of even-numbered intermediate layers counting from the photoconductive layer side, there exists si for enabling the refractive index ni and the thickness di [μm], si being a positive integer at which (2·si−1)/(2·h+1) is not an odd number, to satisfy the following expression (8):

4
⁢
⁢
π
⁢
·
n
i
·
d
i
λ
-
(
2
·
s
i
-
1
)
⁢
π
2
·
h
+
1

≤
π
16
.
(
8
)

### Claim 9 (depends on 8)

The electrophotographic apparatus according to claim 8, wherein si is an integer that satisfies the following expression (9):
Si=Sa+(2·h+1)mi (9)
where sa is a positive integer at which (2·sa−1)/(2·h+1) is not an odd number and mi is an integer equal to or more than 0.

### Claim 10 (depends on 8)

The electrophotographic apparatus according to claim 8, wherein si is smaller than (16·h+9)/2.

### Claim 11 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein N is an integer that satisfies the following expression (6):
N=4·k−1 (6)
where k is a positive integer, and
wherein there exists ui for enabling the refractive index ni and the thickness di [μm] of each of even-numbered intermediate layers counting from the photoconductive layer side, ui being a positive integer at which ui/(k+1) is not an odd number, to satisfy the following expression (10):

4
⁢
⁢
π
·
n
i
·
d
i
λ
-
π
·
u
i
k
+
1

≤
π
16
.
(
10
)

### Claim 12 (depends on 11)

The electrophotographic apparatus according to claim 11, wherein ui is an integer that satisfies the following expression (11):
ui=ua+2(k+1)vi (11)
where ua is a positive integer at which ua/(k+1) is not an odd number and vi is an integer equal to or more than 0.

### Claim 13 (depends on 11)

The electrophotographic apparatus according to claim 11, wherein ui is equal to or less than 8(k+1).

### Claim 14 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein N is an odd number less than 12.

### Claim 15 (depends on 1)

The electrophotographic apparatus according to claim 1, wherein the photoconductive layer comprises a layer including amorphous silicon, and each of the intermediate layers and the surface layer comprises a layer including amorphous silicon carbide or amorphous silicon nitride.

### Claim 16

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
)

### Claim 17 (depends on 16)

The electrophotographic photosensitive member according to claim 16, wherein, for one or more even-numbered layers counting from the photoconductive layer side, there exists qi for enabling the refractive index ni and the thickness di [μm], qi being an integer equal to or more than 0, to satisfy the following expression (5):

4
⁢
⁢
π
·
n
i
·
d
i
λ
-
2
⁢
⁢
π
·
q
i

≤
π
8
.
(
5
)

### Claim 18 (depends on 16)

The electrophotographic photosensitive member according to claim 16, wherein N is an integer that satisfies the following expression (7):
N=4·h+1 (7)
where h is a positive integer, and
wherein, for each of even-numbered intermediate layers counting from the photoconductive layer side, there exists si for enabling the refractive index ni and the thickness di [μm], si being a positive integer at which (2·si−1)/(2·h+1) is not an odd number, to satisfy the following expression (8):

4
⁢
⁢
π
·
n
i
·
d
i
λ
-
(
2
·
s
i
-
1
)
⁢
π
2
·
h
+
1

≤
π
16
.
(
8
)

### Claim 19 (depends on 16)

The electrophotographic photosensitive member according to claim 16, wherein N is an integer that satisfies the following expression (6):
N=4·k−1 (6)
where k is a positive integer, and
wherein there exists ui for enabling the refractive index ni and the thickness di [μm] of each of even-numbered intermediate layers counting from the photoconductive layer side, ui being a positive integer at which ui/(k+1) is not an odd number, to satisfy the following expression (10):

4
⁢
⁢
π
·
n
i
·
d
i
λ
-
π
·
u
i
k
+
1

≤
π
16
.
(
10
)

### Claim 20

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
)