Drum unit, image forming unit and image forming apparatus

1. A drum unit, comprising:

a photosensitive drum, and

a cleaning member that is arranged to contact to a surface of the photosensitive drum, wherein

a scratch remaining depth measured by a scratch test of the photosensitive drum under a following Test Condition 1 is 110 nm or less,

Test Condition 1 is:

test environment temperature=25° C.;

test environment humidity=50%;

test indenter=pre-mount type Berkovich indenter;

scratch direction=horizontal direction;

scratch speed=20 μm/sec;

initial load=0 mN;

maximum reaching load=4 mN; and

load at the time of measuring the scratch remaining depth=1.9 mN.

2. The drum unit according to claim 1 , wherein

a Martens hardness of the photosensitive drum measured by a push-in test under a following Test Condition 2 is ranged between 100 N/mm 2 and 170 N/mm 2 ,

Test Condition 2 is:

test environment temperature=25° C.;

test environment humidity=50%;

indenter for testing=pre-mount type Berkovich indenter;

maximum load=4 mN;

load duration=30 seconds;

peak load retention time=25 seconds; and

unload duration=30 seconds.

3. The drum unit according to claim 1 , wherein

the cleaning member is a cleaning blade that is press-contacted to the photosensitive drum.

4. The drum unit according to claim 1 , wherein

the photosensitive drum includes a supporting body and a photoreceptive layer formed on the supporting body.

5. The drum unit according to claim 4 , wherein

the photoreceptive layer includes a charge transportation material and a charge generation material.

6. The drum unit according to claim 4 , wherein

the photoreceptive layer further contains a binder resin in which a charge transportation material and a charge generation material are dispersed.

7. The drum unit according to claim 4 , wherein

the photoreceptive layer includes

a charge transportation layer that contains a binder resin in which charge transportation materials are dispersed, and

a binder resin in which charge generation materials are dispersed.

8. The drum unit according to claim 3 , wherein

the cleaning blade includes

a tip end portion that is press-contacted to the photosensitive drum and

a support portion that supports the tip end portion, and

a surface Young's modulus measured by a push-in test of the tip end portion under a following Test Condition 3 is ranged between 18 MPa and 30 MPa, and

a plastic deformation amount measured by the push-in test of the tip end portion under the Test Condition 3 is ranged between 1 N mm and 4 N mm, and

Test Condition 3 is:

test environment temperature=25° C.;

test environment humidity=50%;

indenter for testing=pre-mount type Berkovich indenter;

maximum load=5 mN;

load duration=30 seconds;

peak load retention time=25 seconds; and

unload duration=30 seconds.

9. An image forming unit, comprising:

the drum unit according to claim 8 ; and

a developer carrier that is arranged to face the photosensitive drum.

10. An image forming apparatus, comprising:

the image forming unit according to claim 9 ;

an exposure unit that exposes the photosensitive drum; and

a transfer part that is arranged to face the photosensitive drum.