Developing device and image forming apparatus that generate prevention bias for suppressing scattering of developer

A developing device for developing an electrostatic latent image on an image carrier by using developer, comprising:

• a developing bias output unit configured to output a developing bias generated by superimposing an AC bias on a DC bias;
• a developing sleeve supplied with the developing bias output from the developing bias output unit;
• a prevention bias generator unit configured to generate a prevention bias by holding a peak value of the developing bias, the prevention bias suppressing scattering of developer carried by the developing sleeve;
• and
• an electrode, disposed at a position opposing the developing sleeve, configured to output the prevention bias,
• wherein the prevention bias generator unit includes:
• a first resistor supplied with the developing bias;
• a diode, with a cathode of the diode being connected to the first resistor in series;
• and
• a capacitor,
• with a terminal of the capacitor being supplied with a potential of the DC bias and another terminal of the capacitor being connected to an anode of the diode, and
• wherein the prevention bias generator unit outputs, as the prevention bias, a potential of the anode of the diode.

An image forming apparatus comprising:

• a forming unit configured to form an electrostatic latent image on an image carrier;
• and
• a developing device configured to develop the electrostatic latent image formed by the forming unit,
• wherein the developing device includes:
• a developing bias output unit configured to output a developing bias generated by superimposing an AC bias on a DC bias;
• a developing sleeve supplied with the developing bias output from the developing bias output unit;
• a prevention bias generator unit configured to generate a prevention bias by holding a peak value of the developing bias of the superimposed AC bias and DC bias, the prevention bias suppressing scattering of developer carried by the developing sleeve;
• and
• an electrode, disposed at a position opposing the developing sleeve, configured to output the prevention bias,
• wherein the prevention bias generator unit includes:
• a resistor supplied with the developing bias of the superimposed AC bias and DC bias;
• a diode supplied with the developing bias of the superimposed AC bias and DC bias, a cathode of the diode being connected to the first resistor in series;
• and
• a capacitor, with a terminal of the capacitor being connected to ground and another terminal of the capacitor being connected to an anode of the diode, and
• wherein the prevention bias generator unit outputs, as the prevention bias, a potential of the anode of the diode.

An image forming apparatus comprising:

• a forming unit configured to form an electrostatic latent image on an image carrier;
• a developing bias output unit configured to output a developing bias generated by superimposing an AC bias on a DC bias;
• a developing sleeve supplied with the developing bias output from the developing bias output unit;
• a prevention bias generator unit configured to generate a prevention bias by holding a peak value of the developing bias, the prevention bias suppressing scattering of developer carried by the developing sleeve;
• and
• an electrode, disposed at a position opposing the developing sleeve, configured to output the prevention bias,
• wherein the prevention bias generator unit includes:
• a resistor supplied with the developing bias;
• a diode, with a cathode of the diode being connected to the resistor in series;
• and
• a capacitor, with a terminal of the capacitor being supplied with a potential of the DC bias and another terminal of the capacitor being connected to an anode of the diode, and
• wherein the prevention bias generator unit outputs, as the prevention bias, a potential of the anode of the diode.