Developing device having developing gap detecting function

A developing device having a developing gap detecting function in an image forming apparatus, comprising:

• a photosensitive medium;
• an exposure member forming an electrostatic latent image on the photosensitive medium;
• a developer conveyer depositing a developer to the electrostatic latent image formed on the photosensitive medium to form a visual image;
• a power supply supplying a voltage to the photosensitive medium and the developer conveyer;
• a current detecting unit detecting a current flowing from the power supply to the developer conveyer when the voltage of the power supply is outputted to develop the electrostatic latent image using the developer;
• and
• a controller controlling one of a peak-to-peak, a duty ratio, a frequency, and a DC overlapped value of an AC voltage component of the power source to control image forming conditions of the developing device, and adjusting the voltage to charge the photosensitive medium, strength of light and a scanning time of the exposure member forming the electrostatic latent image on the photosensitive medium using the light.

A developing device having a developing gap detecting function in an image forming apparatus, comprising:

• a photosensitive medium;
• an exposure member forming an electrostatic latent image on the photosensitive medium;
• a developer conveyer depositing a developer to the electrostatic latent image formed on the photosensitive medium to form a visual image;
• a power supply supplying a voltage to the photosensitive medium and the developer conveyer;
• a current detecting unit sensing a DC current flowing on the developer conveyer when a charged developer moves from the developer conveyer to the photosensitive medium;
• and
• a controller adjusting the voltage supplied to the developing conveyer using the sensed DC current to maintain a density deviation and a line width of the visual image uniform.

A method in a developing device having a developing gap detecting function in an image forming apparatus having a photosensitive medium and a developer conveyer, the method comprises:

• supplying DC and AC voltages to the photosensitive medium and the developer conveyer;
• detecting a value of a DC current flowing on the developer conveyer when the DC and AC voltages is outputted to develop an electrostatic latent image formed on an area of the photosensitive medium using a developer transferred from the developer conveyer;
• obtaining a developing gap formed between the photosensitive medium and the developer conveyer based on the detected DC current value;
• and
• calculating a developing voltage adapted to the developer conveyer to be supplied to the developer conveyer based on the obtained developing gap.