Image forming apparatus

1. An image forming apparatus comprising:

a charger facing a rotatably supported image carrier, the charger being configured to charge a surface of the image carrier on which an electrostatic latent image is to be formed;

a cleaning member cleaning the charger;

a movement mechanism configured to move the charger between a charging position at which the charger is close to the surface of the image carrier and a retracted position at which the charger is retracted away from the surface of the image carrier;

a positioning structure including a first reference member that is provided on the charger and a second reference member that is provided on the image carrier, the first reference member and the second reference member are in contact with each other when the charger is at the charging position such that the charger is held in the charging position and are spaced apart from each other when the cleaning member cleans the charger; and

a pushing member configured to push the charger against the image carrier when the charger is at the charging position.

2. The image forming apparatus according to claim 1 , wherein the movement mechanism includes

a support member supporting the charger and to which a driving force is transmitted from a drive source, the driving force causing the support member to move close to and away from the image carrier; and

a contact member provided on the charger such that the charger is supported by the support member, the contact member being pressed against the support member with the pushing force of the pushing member and configured to move close to and away from the image carrier with a movement of the support member,

wherein the contact member and the support member are shaped such that the contact member and the support member are spaced apart from each other when the charger is at the charging position.

3. The image forming apparatus according to claim 2 , wherein the pushing member is a torsion spring.

4. The image forming apparatus according to claim 1 , wherein the first reference member has a protruding portion and the second reference member has a reference surface, the protruding portion being in contact with the reference surface when the charging member is at the charging position.

5. The image forming apparatus according to claim 4 , wherein the movement mechanism includes

a support member supporting the charger and to which a driving force is transmitted from a drive source, the driving force causing the support member to move close to and away from the image carrier; and

a contact member provided on the charger such that the charger is supported by the support member, the contact member being pressed against the support member with the pushing force of the pushing member and configured to move close to and away from the image carrier with a movement of the support member.

6. The image forming apparatus according to claim 5 , wherein the contact member and the support member are spaced apart from each other when the charger is at the charging position.

7. The image forming apparatus according to claim 4 , wherein the first reference member has a plurality of the protruding portions.

8. The image forming apparatus according to claim 7 , wherein the first reference member is disposed on an end portion of the charger in a direction of a rotation axis of the image carrier.

9. The image forming apparatus according to claim 1 , wherein the first reference member has a reference surface and the second reference member has a protruding portion, the protruding portion being in contact with the reference surface when the charging member is at the charging position.

10. The image forming apparatus according to claim 9 , wherein the movement mechanism includes

a support member supporting the charger and to which a driving force is transmitted from a drive source, the driving force causing the support member to move close to and away from the image carrier; and

a contact member provided on the charger such that the charger is supported by the support member, the contact member being pressed against the support member with the pushing force of the pushing member and configured to move close to and away from the image carrier with a movement of the support member.

11. The image forming apparatus according to claim 10 ,

wherein the contact member and the support member are spaced apart from each other when the charger is at the charging position.

12. The image forming apparatus according to claim 9 , wherein the second reference member has a plurality of the protruding portions.

13. The image forming apparatus according to claim 1 , the charger includes a discharge electrode extending in a direction of a rotation axis of the image carrier, the discharge electrode being held to the charger by the first reference member, the charger being configured to apply voltage to the discharge electrode.

14. The image forming apparatus according to claim 1 , wherein the pushing member is a torsion spring.

15. The image forming apparatus according to claim 1 , wherein the image carrier has a support member provided at one end of the image carrier in a direction of a rotational axis to support the image carrier, and

wherein the second reference member is on the support member.