Patent ID: 8311427

Claim:
An image forming device, comprising: an image carrier; an exposure device that forms a latent image on a surface of the image carrier; a developer carrier that develops the latent image and forms a developer image by attaching developer on the image carrier; a developer supplying member that supplies the developer to the developer carrier; a transferring member that transfers the developer image on a medium; a pattern forming processing part that forms a first density detecting pattern with a duty of a high tone and a second density detecting pattern with a duty of a middle tone on a pattern forming medium; a density detection processing part that detects densities of the first density detecting pattern and the second density detecting pattern on the pattern forming medium; a supply voltage changing processing part that changes a supply voltage that is applied to the developer supplying member based on the detected density of the second density detecting pattern by the density detection processing part; and a developing voltage changing processing part that changes a developing voltage that is applied to the developer carrier based on the detected density of the first density detecting pattern by the density detection processing part after the supply voltage is changed by the supply voltage changing processing part and when the formed density of the second density detecting pattern by the pattern forming processing part is equal to or less than a threshold value.