Developing device and image forming apparatus
AssigneeSharp Kabushiki Kaisha
InventorsToshimasa Hamada, Nobuhiro Maezawa
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Abstract
A developing device capable of improving the image density and the dot reproducibility, and an image forming apparatus including the same are provided. A developing device applies an alternating voltage superimposed on a direct current voltage to a developing roller to thereby develop an electrostatic latent image formed on a photoreceptor with toner. A bias voltage waveform superimposed at this time has an original period (first period) in which each of a development-side electrical potential and an opposite development-side electrical potential is applied one time and a period (second period) in which a Vpp is gradually increased from the initial value to the maximum value.
Claims14
A developing device that develops an electrostatic latent image formed on an electrostatic latent image bearing member with toner by applying an alternating voltage superimposed on a direct current voltage to a developer bearing member,
- wherein the alternating voltage to be applied has an alternating voltage waveform in which a development-side electrical potential to move toner from the developer bearing member to the electrostatic latent image bearing member and an opposite development-side electrical potential to move toner from the electrostatic latent image bearing member to the developer bearing member are applied so as to alternate with each other, and
- the alternating voltage has a first period in which each of the development-side electrical potential and the opposite development-side electrical potential is applied once and a second period in which a peak-to-peak voltage is gradually increased from an initial minimum value to a maximum value, and the initial minimum peak-to-peak voltage is applied after the maximum peak-to-peak voltage in the second period is applied.
The developing device of claim D, wherein the alternating voltage includes n pieces of first periods in one period of the second period, and when respective peak-to-pear voltages from the initial minimum peak-to-peak voltage to the maximum peak-to-peak voltage are changed into V(1), V(2), . . . , V(n), with elapse of time, the respective peak-to-peak voltage satisfies the following formula (1):
- V(i)≦V(i+1)
- V(1)<V(n) (1)
- (wherein, 1≦i≦n−1 (i is an integer number).)
Dependencies are inferred from the claim text.