Carrier for developing electrostatic latent images, two-component developer, image forming apparatus, toner storing unit, and supplemental developer

1. A carrier, comprising:

a magnetic core particle; and

a resin layer coating a surface of the magnetic core particle, the resin layer comprising a particulate material A having a volume average particle diameter (a) and a particulate material B having a volume average particle diameter (b),

wherein the volume average particle diameter (a) of the particulate material A is the largest among volume average particle diameters of all particulate materials included in the resin layer,

wherein an inequation 100≥(a)/(b)≥5 is satisfied, and

wherein the particulate material A is barium sulfate.

2. The carrier of claim 1 , wherein the volume average particle diameter (a) of the particulate material A is in the range of from 400 to 1,000 nm.

3. The carrier of claim 1 , wherein the particulate material B has conductivity.

4. The carrier of claim 1 , wherein the volume average particle diameter (b) of the particulate material B is in the range of from 4 to 100 nm.

5. The carrier of claim 1 , wherein the particulate material B is a tin oxide compound.

6. A two-component developer comprising:

the carrier of claim 1 ; and

a toner.

7. The two-component developer of claim 6 , wherein a concentration of the toner in the two-component developer ranges from 3% to 11% by mass.

8. The two-component developer of claim 6 , wherein the toner is at least one selected from the group consisting of a color toner, a white toner, and a transparent toner.

9. An image forming apparatus comprising:

an electrostatic latent image bearer;

a charger to charge the electrostatic latent image bearer;

an irradiator to form an electrostatic latent image on the electrostatic latent image bearer;

a developing device to develop the electrostatic latent image formed on the electrostatic latent image bearer into a toner image with the two-component developer of claim 6 ;

a transfer device to transfer the toner image formed on the electrostatic latent image bearer onto a recording medium; and

a fixing device to fix the toner image on the recording medium.

10. A toner storing unit comprising:

a storing unit; and

the two-component developer of claim 6 stored in the storing unit.

11. A supplemental developer comprising:

the carrier of claim 1 ; and

a toner.

12. The supplemental developer of claim 11 , wherein a content rate of the toner in the supplemental developer ranges from 2 to 50 parts by mass based on 1 part by mass of the carrier.

13. The carrier of claim 1 , wherein the particulate material B is selected from the group consisting of indium-doped tin oxide, phosphor-doped tin oxide, and tungsten-doped tin oxide.

14. The carrier of claim 1 , wherein the volume average particle diameter (b) of the particulate material B is in the range of from 25 to 50 nm.