Sharp Kabushiki Kaisha Corporation

Yoshiaki Kojoh

Hiroshi Ishii

Kuniaki Nakano

Susumu Murakami

Yoshie Iwakura

Takahisa Narikiyo

For an electrostatic latent image formed on an image carrier (), besides an operation forming an 'image forming electrostatic latent image' used to form the primary image, an operation is executed that forms an 'electrostatic latent image for removing developer' for removing developer that resides on a developer supply member () for a predetermined time period onto the image carrier (). Thus, developer is nearly eliminated from residing on this developer supply member () in an overcharged state for a long period of time, and generation of a fogged image is avoided as much as possible.

Image forming apparatus capable of preventing worsening of image quality caused by excessively charged developer

A rise time and/or a fall time of a driving voltage are set to be not less than {fraction (1/20)} of a period of natural oscillation of an ink-jet head. This suppresses a driving voltage, an amount of generated heat, and dissipated power, which increase when there is a loss due to a resistor component of a charge/discharge system, such as wiring or switching elements, caused by a large current that is flown when the driving voltage rises or falls sharply. The rise time and/or fall time may be made not more than &#x2153; of the period of natural oscillation. In this way, 80% or higher efficiency can be ensured for the oscillation energy of piezoelectric elements, which increases as the rise or fall of the driving voltage becomes sharper. Further, the rise time and/or fall time may be set in the vicinity of {fraction (1/20)} of the period of natural oscillation. In this way, the ejection energy of the piezoelectric elements can be saturated almost completely. As a result, less driving voltage, less heat, and less power are required to drive piezoelectric elements, which are used in ink-jet recording apparatuses and other types of apparatuses.

Growing community of inventors

Nara, Japan

Yoshiaki Kojoh