Image forming apparatus with developer collection

1. An image forming apparatus, comprising:

an image bearing member;

a charging member that charges the image bearing member;

a first exposure unit that exposes the image bearing member so as to form an electrostatic latent image on the image bearing member;

a developing unit that develops the electrostatic latent image as a developer image by supplying a developer, charged to regular polarity, to the image bearing member;

a transfer member that transfers the developer image from the image bearing member to a recording material;

a brush that collects a deposit on the image bearing member downstream of a transfer portion of the image bearing member at which the developer image is transferred to the recording material by the transfer member, and upstream of a charging portion of the image bearing member charged by the charging member, in a rotation direction of the image bearing member; and

a second exposure unit that exposes the image bearing member downstream of the transfer portion of the image bearing member at which the developer image is transferred to the recording material by the transfer member, and upstream of the charging portion of the image bearing member charged by the charging member, in the rotation direction of the image bearing member,

wherein the developer remaining on the image bearing member without having been transferred to the recording material is collected by the developing unit,

wherein the brush has a plurality of bristles, and a base fabric that supports the plurality of bristles, and

wherein a penetration level of the brush into the image bearing member is in a range from at least 0.75 mm to not more than 1.75 mm, with the penetration level being a difference between a length L1 when a portion of the bristles exposed from the base fabric is straightened and a shortest distance L2 between the surface of the image bearing member and the base fabric when the brush is installed on the image bearing member at a predetermined installation position.

2. The image forming apparatus according to claim 1 , wherein the brush collects the deposit charged to an opposite polarity to the regular polarity.

3. The image forming apparatus according to claim 1 ,

wherein the brush collects the deposit that lies, in a triboelectric series, further on an opposite polarity side to the regular polarity, as compared with a position of the brush in the triboelectric series.

4. The image forming apparatus according to claim 1 , wherein

the developer has a toner particle that contains a binder resin and a colorant, and

Martens hardness measured under a condition of maximum load of 2.0×10 −4 N is at least 200 MPa and not more than 1100 MPa.

5. The image forming apparatus according to claim 4 ,

wherein the toner particle has a surface layer containing an organosilicon polymer, and a toner core particle covered by the surface layer, and

wherein a number of carbon atoms directly bonded to a silicon atom in the organosilicon polymer is, on average, at least 1 and not more than 3 per silicon atom.

6. The image forming apparatus according to claim 5 ,

wherein a fixing ratio of the organosilicon polymer relative to the toner particle is at least 90%.

7. The image forming apparatus according to claim 1 , wherein a distance from the brush portion of the image bearing member to an exposure portion of the image bearing member of which the second exposure unit exposes is closer than a distance from the exposure portion of the image bearing member to the charging portion of the image bearing member in the rotation direction of the image bearing member.

8. The image forming apparatus according to claim 1 , wherein the charging member comes into contact with the surface of the image bearing member.

9. The image forming apparatus according to claim 1 , wherein a density of the bristles of the brush is 110 to 290 kF/inch 2 .

10. The image forming apparatus according to claim 1 , wherein a density of the bristles of the brush is 110 to 200 kF/inch 2 .